Oz was later awoken when Lacie was dragged into the lowest level of the Abyss by the Chains of Condemnation to have her existence torn apart for her sins of being a Child of Ill Omen. It was Lacie's children that were born while the Abyss ate away at her existence which had awakened Oz, who had his 1st Dimension body returned to the world he'd known while Lacie was alive by her child, Alice. Meanwhile, Oz's Abyss-bound body befriended the other Alice known as The Intention of the Abyss in the new form of the dimension - where the harmony of the Abyss had been forever destroyed - due to the Alices' similarity to Lacie.
Once The Intention had learned of how Alice had made contact with Jack Vessalius in the 1st Dimension, she immediately rushed to retrieve the final fragment of Lacie's existence - which she'd kept safe from the darkness of the Abyss. Although the darkness of the Abyss was still vying for Lacie's soul and was even attempting to devour what remained once again, The Intention revealed to Oz that the fragment of Lacie that she'd saved contained Lacie's thoughts and feelings toward Jack, and that she just knew Lacie would've wanted Jack to know how she'd felt. Feeling indebted to Lacie still, Oz happily accepted his mission, taking the fragment of Lacie that'd been tainted with darkness into his Abyss-bound body to deliver to his 1st Dimension body for Jack to see. While Oz's body in the 1st Dimension was destroyed due to the darkness that spread through his body to destroy the last piece of Lacie's soul, Oz still succeeded in his mission. Oz experienced Lacie's thoughts and feelings about Jack first-hand, mesmerizing him as he listened to the composition Lacie and Oswald had collaborated on, which Jack had named Lacie. Though his debt to Lacie could never be filled properly, Oz would've done anything for Lacie in return for the life she'd given him, sacrificing both his body and his freedom in an attempt to do so, even though his companion could never know the levels of his gratitude herself.
The first time they met (when both Oz and the Intention had lost their respective memories), the Intention of the Abyss thought that Oz was Jack. She seems to think of him as a reincarnation of Jack Vessalius and is thus deeply infatuated with him, and shows jealousy at Oz choosing Alice over her, stating he would "regret it."
Since The Intention's memories have been torn apart, she started to hate B-Rabbit, because she blames him for taking away her beloved twin sister. This was why the Intention later kidnapped Alice and seemingly hated her, as she wanted the powers of B-Rabbit to be torn from Alice so that she could have her Alice back again.
Regardless, he was saddened when the Intention didn't smile that often in the past. After learning about the entire truth of Break's encounter with the Intention, Oz, like Alice, was determined to grant the Intention's wish. After the Intention was able to see Jack once again and told Oz her thanks for granting her wish from 100 years ago, she asked Oz to form a contract with her. Oz complied and asked Alice and the Intention to say his name. Both she and Alice together called out to Oz affectionately as 'our dear black rabbit'. Just when Oz was about to deliver the final blow, tears swelled in his eyes as the Intention smiled happily at him for granting her wish. Despite the fact Oz developed a closer bond with Alice, Oz nevertheless cared about the Intention as well. Oz eventually granted the Intention's wish and freed her.
Jack's relationship with Oz was complicated. Originally, Oz was a chain that was created by Lacie during her attempts to end the Core of the Abyss's loneliness. After the Core embraced Lacie's daughters while Lacie was destroyed from the darkness of the Abyss, Oz became acquainted with her daughters: Alice and the Intention of the Abyss. When the Intention recognized Jack's voice through Alice's body, she asked Oz to give Jack a piece of Lacie's thoughts and feelings, believing that Lacie wanted Jack to know her true feelings for him. Oz accepted this request due to his desire to thank Lacie for bringing him to life. He also saw from Lacie's memories that Jack was someone important to her. Although Oz was aware of the fact that his body will be destroyed after accepting the small fragment of Lacie's soul, due to the darkness of the Abyss trying to destroy all of Lacie's presence, he was successful into giving Jack the fragment of Lacie's soul. However, Oz was unaware that his actions were a horrible mistake.
When the Intention transformed Oz's body (his other body that remained with the Intention) into the chain B-rabbit, Oz once again met Jack after Jack tricked Vincent into opening the Baskervilles's Door to the Abyss. When Jack asked Oz to form a contract with hm, Oz remembered the reason he gave Jack the fragment of Lacie's soul was due to his wish of wanting to repay Lacie for giving him his life. Despite suspicions of whether his latest action of giving Jack the fragment of Lacie's would create a misunderstanding, Oz accepted Jack's request and formed a contract with Jack, before proceeding to destroy the chains wrapping the world.
Oz's worst suspicion was confirmed as soon as Jack mercilessly ordered him to slaughter the Baskervilles who came to aid Glen, as well as injuring and finally beheading Glen. Unknown to Jack, Oz was horrified of the actions he just committed. His cries were heard by Alice who was inside the tower. After Alice confirmed her doubts that Jack was the one responsible for Oz's anguish, she tried to have Jack sympathize with Oz only to have him show his indifference towards Oz and become enraged before trying to make her switch places with the other Alice. When Alice committed suicide in order to protect those she loved- Alice and Oz - Oz could only stare in shock and dismay over the fact that he couldn't stop Jack from hurting Alice. He was severely depressed. Later on, Alice (in spirit) took over Oz's body, taking his powers as B-rabbit and his memories, which released him from Jack.
After the events of the Tragedy of Sablier, in which Jack took advantage and manipulated the truth, Oz remained dormant in Jack's body. After Jack convinced the current head of his family, Xai Vessalius, 100 years later and the last pieces of Jack's soul has disappeared from his body, Oz was woken from his slumber and took control of Jack's body. Because Alice had taken away his memories, Oz was unaware of the truth about himself. When Jack discovered that Xai knew the truth about what really happened at the Tragedy of Sablier, Jack manipulated Xai into believing that by casting him and Oz into the Abyss using the Chains of Condemnation, Xai would be able to get rid of both of them. In reality, Jack was hoping that Xai would cast them into the Abyss, in hope of reuniting with Alice and regaining Oz's powers back.
After returning from the Abyss, Oz saw an image of Jack after the pocket watch fell and one of Alice's memories appeared. Jack told Oz that he's been waiting for him. Jack encouraged Oz to find all of Alice's memories. Jack appeared once more during Oz's attempt to stop Alice from killing Phillipe West's father by telling him he can control Alice's power. Oz finally met Jack during his and Gilbert's rescue attempt to save Alice and Break from Cheshire's dimension. Despite the sudden meeting, Oz believed in Jack when he said he wanted to help him save Alice. Oz, having seen a memory of Alice and Jack together, trusted him and allowed Jack to give him his strength. Jack comforted Oz when he witnessed a scene of the Tragedy of Sablier, as well as when Oz discovered Alice's death scene. After Oz, Alice, Gilbert, and Break escaped Cheshire's dimension, Oz discovered he contained Jack's soul within him during the confrontation with the members of Pandora.
This revelation shocked and surprised Oz. To his dismay, the members of Pandora treated him as someone special rather than a normal person. Oz explained to Reim that it is because they seen him as Jack rather than Oz. Over time, Oz accepted the fact that Jack's soul lived inside him. However, he told Rytas he is just Oz, not Jack, showing that Oz sees himself and Jack as two separate people. Oz sometimes takes advantage of the fact that he has Jack's soul inside of him. An example of this is when Oz tricked Isla Yura into believing that Jack took over his body at the moment Oz tried to kill himself and manipulated him into gaining access to his mansion.
All of this changed during the Baskervilles's attack at the headquarters of Pandora. When Oz managed to get Leo to regain his sanity, Jack took over Oz's body and sent one of B-rabbit's chain through Leo's body, much to Oz's horror. While Oz questioned Jack about his actions, Jack tried to convince Oz to destroy Leo to Oz's refusal. When Oz stopped Jack from harming Leo, Jack was amused when Oz said he is Leo's friend and won't allow Jack to take control of his body. Jack countered this by telling Oz that's impossible because he knows Oz is trying to deny the memories within him. After telling Oz that his existence is nothing and that everything he was had diminished, saying that Oz's existence can't really exist, Jack forced Oz to regain his lost memories.
After Oz regained his lost memories, he was completely devastated by the revelation Jack forced him to remember as well as the events that really occurred during the Tragedy of Sabiler. During the rescue attempt by Gilbert, and later on by Oscar, Oz was able to regain himself after Oscar revealed his wish for Oz to be happy. This allowed Oz to regain control of his body and free himself from Jack's control. Despite Oz hating Jack for everyone he's done, Oz asked Jack to make a deal with him.
During his battle with Oswald (who at the time taken control of Leo's body), Jack once more tried to convince Oz to destroy Oswald to which Oz refused again. During Oz and everyone else's attempt to save Alice and Gilbert from the Core of the Abyss, Jack at first stopped Oz from leaving after the completion of his Incuse. Looking to Oz, Jack asks if it's really okay for him to be doing "it" alone. Confirming this, Oz reveals that he's already said everything he wanted to say to Jack, bidding him farewell as he loosens from Jack's grip and drifts away from Jack's subconscious. This showed that Oz, despite his feelings toward Jack, trusted him for what he's about to do next.
It was revealed that Oz's body was becoming more chain-like as a result of his power and the Incuse on Oz's chest fully completed it's rotation. Regardless, Oz made a deal with Jack: to ask Jack to seek out the Intention of the Abyss and rescue her. Oz wanted Jack to tell the Intention the truth of why the events occurred at the Tragedy of Sablier. Oz is aware of Jack's influence on the Intention and know she whould believe anything Jack said. Intrigued by this, Jack asked why Oz asked for such a request and what Oz do in exchange for Jack's cooperation in fulfilling this request. Oz said he will stop the Chains from being destroyed, to which Jack laughed knowing he was the one responsible for the Chain of the World's destruction. However, Oz explained that while he aware of this, he will show Jack that his actions were a mistake. Oz reminded Jack about the conversation about the Abyss and Jack's reason for why he wanted to destroy the Chains after Lacie's death. Oz told Jack that Lacie never wanted the world she loved to be destroyed and that Jack never understood Lacie's wish in the end. Jack rebuffed Oz's statement, asking how can Oz know such a thing. Oz counters this argument by stating Jack never saw the Abyss in its original form. Oz explained to Jack that Lacie not only loved the world she grew and lived in but the other world she saw: the Abyss itself. Jack claimed Oz is lying but Oz immediately told Jack he isn't lying. Jack knew Oz was telling the truth since Jack himself is a expert of lying.
While Jack went to the Intention, Jack told himself that he had no desire to help Oz and fulfill the deal they made. Jack wanted to continue his plan to destroy the Chains. However, Jack found himself questioning his reason for doing all of this. After remembering a memory he had with Lacie shortly after they met, Jack found himself hesitating and instead told the Intention the truth, much to his confusion. To Jack's surprise the Intention forgave Jack for his actions and told Jack she was happy to have met him. After the Abyss was restored to its original form after the Intention's death, Jack finally realized his mistake and finally understood that Lacie would never want the worlds she knew to be destroyed. Jack thanked Oz and Alice for showing him the error of his ways. When Oz told Jack once again how he hated him, yet at the same time believed Jack could have chosen a different path, Jack at first was about to agree with Oz. However, Jack said it isn't possible since he was too mesmerized by the image of Lacie dancing in blood. This saddened Oz.
Oz has a very strained relationship with his father. Originally, Xai was approached by a child with blonde hair and green eyes, who claimed that he was Jack Vessalius. Jack told his descendant that it was a pleasure to meet him and for Xai not to be afraid - instead urging Xai to listen to what he had to say. Xai complied, allowing Jack to explain how within his body slept the soul of B-Rabbit, a Chain that had nearly destroyed the entire world more than one-hundred years before. Jack explained in detail how his body had been rejected by the power of the Abyss, having instead forced his body to rewind its physical age and then begin aging once more in a continuous repetitive cycle, because he'd come into contact with The Core of the Abyss. Jack added that the cycle was gradually destroying his soul with each progression, and so his soul was destined to vanish from existence once-and-for-all.
Jack then posed a proposition to Xai - asking Xai to take his body as 'Oz' once it'd reverted to the form of a baby, introducing it back into the Vessalius Dukedom in place of Xai's own child, which Jack knew was going to be stillborn. Although curious, Xai was skeptic of everything that Jack had told him. Jack left the offer on the table - letting Xai go to Rachel's side as she went into labor. It turned out that Jack's prediction was true, with Xai's child being born in death's embrace. Furious over the loss of his son and not wanting to see Rachel distraught over her son's death, Xai angrily stole the body of his dead son from Rachel's arms while she slept, storming off into the night to seek out his ancestor.
Xai found Jack, his body having been reverted back to the form of an infant and his soul having been vanquished almost completely, fulfilling Jack's wish by switching his dead son with the young body of Jack Vessalius. Xai returned to the hospital, facing extensive questioning because of his actions. Xai had thought of this however, telling anyone who asked that he wanted to celebrate the christening of his son on his own. Although Xai was angered by his son's death, Xai also saw opportunity from switching his son with Jack - thinking that he could obtain information from Jack as he grew. Later, when Rachel awoke, Xai submitted to Jack's wish completely by insisting that they name the child Oz; acting as though nothing had changed in order to spare his wife from heartache.
Tragically, Xai began to regret his decision when misfortunes occurred around his family. After his wife died in an accident a few days after giving birth to their second child (Ada), Xai began to suspect that Jack was the one responsible for the accident. His suspicions proved to be correct as Xai discovered the truth of what Jack did during the Tragedy of Sablier. His hatred toward Jack grew more after his brother (Oscar)'s wife and unborn child died during childbirth. Although Xai was indifferent to his brother's wife, he nonetheless blamed Jack for her death and her child's death as well. This led to the process in when Xai began to dehumanize Oz in hope of hurting Jack.
Since Oz lost his memories as a Chain, he began to believe that he should love his father. Due to his lack of knowledge of the truth, Oz was deeply hurt and confused as to why Zai always ignored his presence. Xai's repeated that he was a filthy child and that he should have never been born, which deeply traumatized Oz. When Gilbert attempted to convince Oz's suspicious that his father hated him wasn't true, Oz was hurt and shocked when his suspicious was proved to be correct. After Xai rejected Oz's gift and repeated his usual words toward Oz, Oz knew right away that his father hated him and wanted nothing to do with him. Devastated by this revelation, Oz cried while wondering what he did to cause Xai to hate him so much.
After spending fifteen years successfully hurting Oz, Xai joined forces with the Baskervilles so that they could confirm that Oz was the child mentioned in the prophecy, and subsequently cast Oz into the Abyss as a result. Although Xai would've much rather have had Oz killed, he knew that something like that would have been impossible without the Intention of the Abyss intervening because of her connection to Jack, and so Xai had to settle for Oz being trapped in the Abyss. Even after Oz came back from the Abyss, Xai made no effort to visiting or seeing him again.
After Elliot, Leo, Oz and Gil had all met up in The Hole, Xai appeared to retrieve Elliot, as Bernard couldn't do it himself. Elliot declined, saying that he would never accept help from a Vessalius and that Xai should be offering to help his son. Xai simply smirked and said that he didn't care what happened to "that thing". Elliot, enraged, began yelling at him, only to be stopped by Leo, who apologized to Xai. Xai remarks on how smart a servant Elliot had before leaving.
Gil ran after Xai and held him at gunpoint, because of how he'd hurt Oz. Xai expected this and recalled how Gilbert had held him at gunpoint before shortly after joining Pandora, threatening to kill Xai if he ever came anywhere near Oz again. Gilbert then went over the events that happened after Oz was cast into the Abyss. Gilbert was the only one who remembered what had happened. He told Oscar that Oz had been cast into the Abyss and that it was his own father who'd done it, but when Oscar looked into the matter, Bernard Nightray provided an alibi for Xai, saying that he was with him at the time of the Coming of Age Ceremony. Oscar accepted this but he didn't realize that Bernard was also secretly involved with the Baskervilles. Xai summoned Gryphon and confirmed again to Gilbert that it was he who cast Oz into the Abyss 10 years ago. Gil attempts to shoot Xai, and Gryphon prepares to defend it's contractor but Mad Hatter appeared between the two and stopped them from fighting. Break then appeared behind Gil and pulled him away while Xai proceeds out of the Inner Hole. Gil later admits that he wouldn't have been able to kill Xai because it would've hurt Oz too much.
Xai finds Ada with Oz and Noise, seeing that Noise intends on torturing Ada with Oz's death and then killing Ada herself. Xai draws his gun and shoots Noise from behind before she can accomplish her sadistic goal. While Oz attempts to absorb Xai's presence, Xai shoots at him - missing only slightly. Meanwhile, Noise is crying out in agony on the ground, using Duldee and Duldum to send Ada to kill Xai for shooting her. Xai manages to stop Ada from stabbing him with a shard of class, trying to get Ada to break free of Duldee and Duldum's control by reminding her of who he is.
Suddenly, a Chain jumps down between them, sending both Xai and Ada flying backwards. Ada is knocked unconscious as Duldee's strings are severed thanks to the Chain, freeing her from Noise's control. The Chain then charges after the dazed Ada, and although Oz attempts to save Ada himself, Noise impedes his attempt with an attack of her own. Xai stands and runs to Ada instead, putting himself between her and the Chain; resulting in Xai taking the Chain's clever in his back for his daughter. Having witnessed Xai's compassion, Oz is stunned by Xai's compassion, managing to escape Noise and kill the Chain once and for all with the power of B-Rabbit soon after.
With the Chain's existence crumbling and Noise having fled, the threats have gone and so Xai can rest, propping himself up against a nearby wall. Xai notices that Oz is crying, wondering if Oz pities him. Oz quickly denies it, instead claiming that he's sorry that he never truly got to know Xai, and how there were so many things he would've liked to speak with him about. Xai just lashes out that they could never understand one another because he'll never forgive Jack for what he did to the Vessalius Dukedom. Furthermore, he'll never accept a Chain like Oz intending on cursing both Oz and Jack until the moment he draws his last breath. Falling to his knees, Oz declares that Xai's hatred doesn't matter, presenting himself to Xai as someone who's finally able to understand that it's okay for him to be there, which is why he has to go. Oz bids farewell to Xai, carrying Ada on his back through the streets of Sablier's black city, leaving Xai to be alone. Once alone, Xai slides down the wall he was using for support, with blood dripping onto the ground below as well as plastering the wall behind him, saying goodbye back to Oz and Ada as Oz left him alone to die.
Oscar took the role of acting a parental father figure for Oz since his brother made no attempt to do. In turn, Oz viewed Oscar as a father figure and deeply loved his uncle. Although Oz wanted his uncle to take a picture of him with his camera, Oscar promised Oz that he will do so as he wanted the first photo to be his wife and their child when he was born. After Oscar's wife and son dies during childbirth, Oscar met Oz in the hallway who was holding on to his sleeve, unaware of the events that had occurred. Although Oscar was burdened by Oz's attempt to comfort him, he was nevertheless touched by Oz's gestures.
Oscar even took it upon himself to one day confront Xai about his treatment of Oz, saying that he'd had enough of it. Oscar told Xai that all Oz had ever done is tried to get Xai's attention, and so Xai couldn't neglect him anymore. Xai asked what Oscar was talking about, because to Oscar, Oz was nothing more than a replacement for his dead son. In other words, Oscar was only using Oz as a means to fill the gaping hole which Sara and his son's deaths left in him. Xai stood and walked past Oscar, telling him not to make Xai laugh by preaching to him. Xai's words had been harsh, but Oscar could not deny the truth in them. Oscar thought of how from time-to-time he wondered why Oz was there with him instead of his own son. Oscar thought of how Oz was clever and sensitive, as well as how he needed to rid his mind of his dark thoughts; otherwise he'd be running the risk of one day hurting Oz.
One day, Oz overheard Oscar's conversation with one of the servants to dispose his camera in reaction to his wife and child's death. Knowing firsthand how much the camera meant to his uncle, Oz was determined to save the camera from being dispose of. A few nights later however, Oscar returned to his bedroom to find Oz jumping out the window. Oscar immediately ran outside alongside numerous valets. Oscar voiced his concern about Oz, slapping him because Oz had not concerned himself with the consequences that could have followed if Oz had not been lucky enough to fall in the bushes below Oscar's window.
Oscar noticed his camera in the bush beside Oz, realizing that Oz had tried to take the camera, but not understanding why Oz would do something so stupid for a stupid toy like the camera. Oscar goes to retrieve his camera, prompting Oz to cling to his uncle and beg forgiveness. Oz promised to never do something so stupid again, begging Oscar not to get rid of his camera. Oscar asked Oz to repeat himself, and Oz explained that he had heard Oscar tell a valet to dispose of his camera, which Oz didn't want to see Oscar do. Oz began to cry as he justified the need to keep the camera, as even though it had never been used, it was still a medium for Oscar's feelings. As Oz continued to cry, Oscar found himself unable to bear with the burden of Oz's feelings, and so he left without saying a word to Oz.
Oscar ended up on a staircase within the Vessalius Dukedom, where he began to cry himself and think of how he should have patted Oz on the head and comforted him. Oscar became consumed with self-pity, calling himself pathetic. However, Oscar had decided that the time had finally come for him to stop philosophizing right and wrong; as even though Oz's presence was a burden, it was also what had anchored him for so long from being lost because of his family's demise. As a result of Oz's reaction, rather than getting rid of his camera, Oscar placed his camera in storage.
When Oscar brought the camera out from years of storage, Oz was at first against the idea of using it for the Unbirthday party. Much to his surprise, Oscar happily declared that Oz was his son. During the events when the Baskervilles took control of Pandora headquarters, Oscar along with Ada was shocked upon learning the truth from Xai about what Oz really is. Even when Xai told Oscar that Jack was responsible for the deaths that had occurred in their family (Ada's mother, Rachael and Oscar's wife Sara along with their son), Xai couldn't accept it. Knowing this, Xai bluntly told Oscar that unless he kill Jack himself, Ada will remained here with the Baskervilles as their hostage. Disgusted of how Xai was willing to use Ada as a bargain chip to convince Oscar to help them, Oscar begrudging accepted to their demands. Before he left, Ada ran up to him and told him to achieve his goal no matter what. Knowing that her father won't kill her, Ada told Oscar that she wants to fight alongside with him before the Baskervilles escorted her away. Remembering all the time he spend to protect Ada and Oz, Oscar was grateful of Ada's words of courage and heading to where Oz and Giil may be.
When Jack once again took control of Oz's body, Oscar was determined to stop Jack from controlling Oz. Despite Jack teasing Oscar about knowing the truth of Oz and how he was responsible for the death of his family, Oscar nonetheless ignored Jack's claims and remain focused on his goal to save Oz. After pinning Jack to the wall, Oscar was surprised that even to this moment, Jack was completely hollow as a person. Sensing neither malice or good will from him, Oscar questioned what Jack really is; after comparing him to the surface of still water, Oscar came to the same conclusion Oswald had about Jack from their first meeting: Jack was empty. This took Jack by surprise and upon recalling the words Oswald once said to him, stabbed Oscar with one of B-Rabbit's chain. Although Oscar was injured, he was able to told Oz what his wish is: that his wish is for Oz to be happy. Oz was surprised by this words and upon remembering everything his uncle did for him, especially the Unbirthday party from before, Oz began to cry. Oz confronted Jack about his previous claims that Oz never have anything and everything Oz have was fake; Oz now knew this wan't true at all and use his own light to destroy Jack's consciousness for the time being. After Oz and his friends reached their destination, Oz was horrified to see Oscar stab from Echo (who was later revealed to be actually Noise in control). Oscar convinced Gilbert and Alice to escape without him despite Oz's pleas. Oz was devastated by this act as he knew in his heart that Oscar will be killed for helping them to escape.
Ada is Oz's little sister, who looked up to him while he treated her fondly. Before Oz (then 15) was sent to the Abyss, they always played together in the castle. Oz met her again 10 years later after he escaped the abyss. Despite not being real siblings, they truly care for each other. When Oz was gone, Ada attempted to rescue Oz by researching and studying about the Abyss in secret since no one would reveal any information to her. Upon meeting each other again after 10 years, Ada cried in happiness while Oz comforted her gently and noted that though she had matured and became different, she was still the same inside. Oz was very worried when Ada got kidnapped by Zwei as later on he retrieved her from Xai, and said to her tenderly that he was happy that their father loved her, despite him not being in the relationship itself.
Oz meet Gilbert when his uncle Oscar introduced him for the first time and told him that Gilbert will be his valet from now on. After Oscar explained to Oz and Ada how Gilbert was found injured and suffered from amnesia, OZ took notice of Gilbert's fragile state. He tried to cheer Gilbert up by asking him to sign a contract in order to formally become his valet. When Oscar began to leave and Gilbert tried to follow him only to knock a vase, Oz protect Gilbert with his body. Gilbert was surprised by this and formally apologized to Oz when he noticed Oz was bleeding. Even though Oz told Gil he's fine, this made Gil upset. Gil said to Oz that "You must not protect someone like me... Because it is my duty to protect my "master"!" Oz hits him on the head, saying that as the master, it was his job to protect Gil now, no matter what. This led to the beginning of Oz and Gil's relationship as master and servant, especially their friendship.
Shortly after they met, Gilbert frequently suffered from nightmares and would occasionally go to Oz to see if he is okay. Oz understood at the time that Gil was afraid of something and constantly worried for his safety; he knew that if something were to happen to him. Gil's fears would come true. He tried to cheer Gil by taking him to Oscar's room. When Gil called Oz "master" on their way to Oscar's room, this stopped Oz and he informed Gil the truth. Every time Oz thinks of how when Gilbert calls him master, at first it made him feel awkward, but after a while, Oz became more adjusted to it because it made him feel like an adult. Gilbert asks if he had done something wrong and Oz thinks of how what he'd just said to himself wasn't quite right. Oz then demands that Gilbert refrains from calling him master anymore, instead he wanted to be called Oz. Oz thinks of how in Holy Knight, Edgar calls his master, Edwin by his name.Gilbert asks why, again calling Oz 'master', and Oz interrupts by yelling the correction of 'Oz' at Gilbert. Gilbert once again used master when he went to say it was impossible, and Oz met him with the same reaction, again and again. The two pant heavily after the continuous routine until Gilbert calls Oz 'Young-master Oz', which Oz decides will do for now. Oz states hat the rest is like homework for Gilbert, as until they were adults, Gilbert would have to learn how to call Oz by his name, which Gilbert agrees to.
As the years passed, Oz and Gilbert formed a close bond with one another. Although Oz sometimes took advantage of Gilbert's timid and shy personality (especially his fear of cats), Oz deeply cared about Gilbert. On the day of Oz's Coming of Age cermony, Oz gave Gil the box Oscar brought for him which Gil was surprise to find out it is an uniform similar to Oz's outfit. Oz told Gil that he wants him to be at the ceremony as his friend rather than his servant. Gilbert was at first reluctantly to complied to Oz's wish. However, he was happy that Oz see him
Oz's relationship with Noise is barely explored at all. At first she merely wanted to toy with him and casted him to the Abyss. However, later on it was revealed that Noise, like the other Baskervilles, viewed Oz as a threat to their plan. Noise is aware that Oz care for Echo a lot.When Noise injured Oscar, Noise expressed delight of the act she had just committed to Noise in her subconscious later on. During Noise's attempt to kill Ada, Oz intervened in her plans. Upon noticing that Echo didn't want to see Oz due to her guilt of killing Oscar (as a result of Noise taking control of her body), Noise was delighted to tease Oz about Echo's guilt and remorse.
Phillipe West reminds Oz of himself after he saved Phillipe from a bunch of orphanage kids. In the massacre that took at Isla Yura's mansion, Oz makes Phillipe break down by telling him the truth "your father is dead!".
Echo and Oz are both mainly seen as companions in the series but there relationship could be called as two people that care deeply for each other when Echo ends up dying in Oz's arm after defeating Noise and Duldum. Oz stated that he had deep feelings for Echo when he met her in the festival.
As time goes on, he grows more fond of Echo, calling her "Echo-chan", to which she grumpily replies: "It's just Echo". When he was captured, Echo bribed Lottie with a bear in order to talk to Oz alone. When she tried to tell him a familiar story, he laughed when she couldn't remember the punchline (because Gil had told it to her and he couldn't remember it himself) and he thanked her for coming to see him, claiming to feel a little better.
During the final battle, when Oz comes across Echo, he encourages her not to give up and watches as she destroys herself to protect Noise. Oz watched as Echo began to crumble into dust, saying he would call out her name no matter how many times and refers to her as "Echo-chan" once more. As Echo looks up at him with a slight blush, she corrects him, saying: "It's just Echo". After Echo's ultimate demise, Oz takes her red cloak and dons it upon himself, showing how close Echo was to him.
In his "memory", he sees Echo at the second "Unbirthday" party, wearing a elegant dress and he calls her out. As he compliments her, she blushes and looks away from him.
Oz wanted to become close friends with Elliot, despite the two being opposing families. Through all of Elliot's rough talk and trying to push Oz away, the two become very close friends (even when Elliot tries to deny it). When Oz hears of Elliot's death, his mind nearly breaks down and became reserved for days.
Leo was the first person to find out about Oz and Gilbert's relationship.