Lacie was Oswald's younger sister. When Lacie first met Jack, she explained that she had run away from the Baskerville mansion because she and Oswald had a disagreement and that she wasn't going back until he apologized. A group of Baskervilles was sent to retrieve Lacie, extending Oswald's deepest apologies to her so that she would return. When Jack embraced Lacie eight years later at an event organized by Arthur Barma, Oswald quickly dispatched Jack, using the end of his knife to knock Jack unconscious, showing that he cared deeply for the safety of his younger sister.
Oswald is protective of Lacie, and he keeps her nearby when possible. His attachment to Jack adding to more company for her, seems to be a very small concession; as well as will help him to better understand his friend who grasps at his intellect, showing only a bright naive smile and the singular devotion to his sister.
Lacie shows no hard feelings towards Oswald after it is revealed that he will have to kill her. However, Oswald is not enjoying the fact that the ceremony is coming up; worried for his sister and horrified in his own, silent way. Oswald managed to tell Lacie that he'd miss her a few days before her death, and after her death, Oswald was hurt emotionally, wanting to carry the burden of Lacie's death by himself. Oswald blamed himself for Lacie being born as a Child of Ill Omen, despite the fact that Lacie told him not to do exactly that.
100 years later Oswald discovered that, through an experiment with the Glen before him, Levi Baskerville, Lacie was partly responsible for the creation of the Intention of the Abyss which warped the golden paradise the Abyss used to be into the chaotic prison it is today after one of her twin daughters, whom she had given birth to in the Abyss as she was destroyed by the darkness, fused with the Core of the Abyss creating Alice (the Intention) with the other girl also named Alice was ejected from the Abyss after they were forced to age physically by 13 years. Although Oswald was aware that this only happened due to Levi manipulated Lacie into helping him and taking advantage of Lacie's desire to end the Core of the Abyss's loneliness, he nevertheless made the choice he believed is right: he will kill Lacie before she and him (his child self) ever joined the Baskerville Clan. That way, her daughters (Alice and the Intention of the Abyss) and Oz the B-Rabbit will never born. The Abyss will remained the golden paradise it used to be and the Tragedy of Sablier will never occurred. Thus, preventing all the people who were killed by his servants and those who have fallen into the Abyss from becoming Chains at all. This decision become important for Oswald since he knew that Jack was successful at destroying the Chains (Stabilizing Force) and it was only a matter of time before the world is destroy.
The most possible negative impact this information had on their relationship is when Oswald discovered that his sister's existence was never a sin. It was merely a lie created by Jury to justify killing Lacie and the other Children of III Omen to prevent them from interfering with her plans for her 'story'.
Oswald displayed his rage over the suffering Lacie went through because of this lie when he attacked the Jury of his world and asked her if she was even capable of feeling pain or fear. This implies that no matter what, Oswald will always care about his little sister and is only trying to kill her to prevent the destruction of their world. This is proved to be true when Oswald tried to kill Oz. However, upon Alice immediately standing in front of him to prevent him from harming Oz, Oswald instead saw a vision of his sister. This caused Oswald to stop his attack instantly even though he had the chance of destroying Alice and Oz. After Alice was taken away by Cheshire, Oswald escaped while thinking why he wasn't able to deliver the flow, meaning that he subconsciously does not want to kill Lacie.
This was the truth during Oswald's fight with Oz at the tower and Leo stopped Oswald in order to confront him. Leo told Oswald that even though he planned to kill Lacie, in reality Oswald hoped that someone (Oz) who is more determined to the point that their feelings outweigh his will stopped him in his path. Upon hearing Leo's words, Oswald remembered his conversation with Lacie about the Core of the Abyss and the Core's loneliness. Oswald remembered his guilt of not acting his role as Lacie's brother and being unable to prevent Lacie from being cast in the Abyss. After witnessing Lacie's memories in the time vortex, especially the memory of Lacie apologized to her brother's future self with a sad expression on her face on the day of her judgment, Oswald was finally able to understand what Lacie said to him on that day. Yet at the same time, he wondered why Lacie was apologizing to him, asking her not to smile at him with that sad expression on her face. Oswald became overwhelmed with his emotions. Upon arriving his destination and seeing Lacie's younger self in front of him, Oswald find himself unable to harm Lacie and finally accepted the truth: he is unable to kill his own sister. After watching the conversation between him and Lacie, as well as seeing Lacie's younger self waved happily at him, Oswald smiled with a look of satisfaction. Oswald was finally able to forgive Lacie in her role of changing the Abyss itself.
Oswald was Levi's personal attendant, always appearing by his side and following his every word. Oswald was confused when Levi asked him if he had feelings for Jack, not understanding what he said or why he laughed after that. The two seem to have a friendly relationship, since Oswald was kept close to him throughout his childhood, and his acceptance into the Baskerville house with his sister, Lacie. Oswald is obedient to his master, even though his order would be a heavy task, taking the life of his younger sister.
Although Levi and Oswald seemed to have a calm and trusting relationship, it was shown that Levi didn't trust Oswald with the information about Alice, Levi's newly born daughter, because he knew that Oswald would do something about Alice because it would have been his duty to do so. Oswald took it upon himself to take care of Alice because of how much she reminded him of Lacie, however he never knew that Alice's existence, alongside her sister's, was Levi's doing which had lead to the destruction of the harmony the Baskervilles kept in the Abyss.
Whilst inside Leo's subconscious and Oswald regained his sense of self following the destruction of the final Sealing Stones, Levi's soul smiles at Oswald's as he prepared to take complete control of Leo's body. However, Oswald now knowing the truth, was unable to forgiven Levi for what he had had done with Lacie, creating the Intention of the Abyss and destroying the golden paradise of the Abyss, as well as giving Jack the tools for starting the Tragedy of Sablier, Oswald simply glared back at Levi hatefully.
Oswald got along well with Alice as seen at the end of Retrace LXIX. He would always bring her food and take care of her as he felt it was his 'duty' to. Though he rarely, if ever, let her leave the tower on the Baskerville mansion grounds. She named Oz the B-Rabbit after Oswald, but Levi corrected her mistake on spelling his name from 'Os' to 'Oz' as Oz would have been the correct way of spelling the name.
Despite any fondness Oswald may have for his niece however it hasn't stopped him from deciding to kill Lacie before she can give birth to the Alice twins, knowing this would not only erase the Intention of the Abyss from existence, but Alice and B-Rabbit as well.Kevin Legnard that she loathes Oswald because he had tried to take Jack away from her. Even before she initially got to know her uncle, the Intention had disliked Oswald, never enjoying spending time with him or Levi whenever she would use Alice's body to visit Earth.
In reality, this feeling of dislike is mutual, as Oswald hates the Intention and believes that she should be destroyed for having shattered the harmony of the Abyss which the Baskervilles had always kept, making Chains more unruly and the Abyss a chaotic prision which not even the Baskervilles are able to navigate in any more. Now knowing fully that Levi and Lacie were responsible for the Intention's manifestation following the destruction of the final Sealing Stone, Oswald intends on returning back to his time 100 years ago in order to kill Lacie before she can give birth to the Alice twins and thereby create the Intention of the Abyss.
|“||To me... Jack Vessalius... feels like water. Like a stretch of water so silent and still, even fish avoid it. When you look into it, the only thing you see is your own reflection. You can't see his true nature. Even though he's right in front of me… I can't shake the uncomfortable feeling that no one's actually there.||”|
—Oswald describing how he sees Jack.
Jack is frightened at Oswald's need to sense his nature, as he had given up on ever understanding himself long ago. At times he can't stand that Oswald will not give up, and that he has no idea who he actually is as a person. After his reunion with Lacie, he grows attached to Oswald and enjoys his company, though he seems constantly stressed by Oswald's stare. He does not ask Oswald many questions pertaining to this extraordinary atmosphere, majorly because he believes Lacie will try to leave him out again. He shares a mutual devotion to Lacie, and through her, her brother, Oswald, who is his first and only friend.
Oswald, after Jack asks him to explain himself for stopping the destruction of the chains, becomes increasingly angry at Jack for betraying him, calling Jack a bastard.
During the confrontation in the forest, Jack confessed to an injured Oswald that he thought Oswald as a dear friend. However, his love for Lacie overshadowed any other feelings, as he was not hesitant to kill Oswald right that moment, for hindering him. B-Rabbit was ordered to finish Oswald. Jack then stood signing with tears, and claimed he was afraid and didn't know if any of his feelings are true, besides that for Lacie.
In the end, as Oswald's soul disappears from Leo's subconscious, Jack watched bewilderedly within Oz's subconscious. Tears dripped down his face when Oswald was gone completely. When asked by Oz whether he was sad, Jack replied dryly that he didn't know, but tears wouldn't stop falling.
Raymond and Oswald were good friends as the Nightrays and the Baskervilles had a good relationship with one another. When the time came for Gilbert to have his first Succession Ceremony and inherit Raven from Oswald, Raymond was to lead the Nightrays and guard the Baskerville's Door to the Abyss while the Baskervilles were at the Ceremony, though this time, Raymond became slightly more involved. Raymond begged Oswald to cancel the invitations that he had extended to the Barma and Vessalius Families, as despite both of them having good relationships with the families, Miranda Barma and Jack Vessalius gave Raymond an ill feeling in his chest whenever he saw them. Oswald was considering Raymond's request, but in the end did not listen to Raymond's warning as he discovered how important to Gilbert it would be if Jack was at his Succession Ceremony. Raymond's ignored warning is what allowed Jack and Miranda's conspiracy against Oswald come to fruition as both were allowed to be on the Baskerville estate for the Succession Ceremony, which lead to the Tragedy of Sablier.
Following the Tragedy of Sablier, it was Oswald and Raymond's former relationship that lead to Jack feeling the need to spread rumours about Raymond that stated that Raymond was a traitor who had helped rebels who had been trying to over throw the government of Sablier during the turmoil of the Tragedy of Sablier escape the crumbling city unharmed. Despite not having done so, Raymond and his family were penalized by the public because of what Jack felt was necessary to do to to Raymond, whom he viewed as his enemy because of Oswald's relationship with him.
Oswald did not know Miranda had an obsessive love for him and that she wanted his head. The two of them spoke after Gilbert's Succession Ceremony was interrupted, and something that Miranda said made Oswald smile. Oswald and Miranda have yet to actually interact past this point.
Gilbert was Oswald's servant from before the hundred-year time skip and was in line to become the next Glen Baskerville. Gilbert was incredibly loyal to Oswald and cared about him deeply, and in return it seemed as though Oswald held a slight soft spot for Gilbert as well, not showing his usual coldness to him and instead showing a certain amount of sympathy. Gilbert also mentions that although he likes Jack very much as well, he likes Oswald much more.
It is later revealed that Jury cursed Gilbert with an oath on his left hand that prevented him from disobeying Oswald until his reign as Glen Baskerville was over. This doesn't appear to have anything to do with Gilbert's loyalty towards Oswald, however.
After Gilbert regained his memories, his loyalty to Oswald seemed nonexistent, as he no longer believed that Oswald's actions were justified and was disgusted by him. However, due to the oath on his left hand, Gilbert was forced to shoot Oz on Oswald's command. After realizing why Gilbert had been forced to do this whether he liked it or not, Gilbert used Raven's flames to burn off his left arm, ultimately choosing Oz over Oswald and leaving the Baskervilles altogether. Oswald does not appear to be very affected or surprised by this, despite the fact that there was an extremely small moment where he appeared mildly surprised, and promptly ordered Oz and Gilbert to be killed.
After this point there does not seem to be a specific relationship between Gilbert and Oswald, as they now have an antagonistic relationship that is not explained in detail. Gilbert doesn't seem to have any regrets about betraying Oswald and the Baskervilles for Oz, nor does he think about it. He explains this to Oz several times.
Oswald and Oz have antagonistic relationship that is not explained in detail. They almost never interact directly, but are usually involved with each other indirectly. Oswald does not seem to know very much about Oz, whether it is in general or as a person, but has taken it upon himself to get rid of him since he was one of the beings heavily involved with the Tragedy of Sablier. Interestingly enough, it's hinted at that Oswald may know more about Oz than is shown, because when Oswald sees Oz he remarks on how the B-Rabbit is alive--although Oz is still in his human form. It is interesting that Oswald is able to recognize Oz even in this form, but it's very possible that Oswald only has this extensive knowledge due to what he knows about Jack and Chains in general.
As Rufus had alligned himself with the Baskervilles after he'd finished decoding Arthur Barma's Memoirs and uncovered the truth about the Tragedy of Sablier, Rufus now often meets the demands of Oswald. When Oswald requested that Rufus shared with him the entirety of Arthur's Memoirs, Rufus complied and read to Oswald whilst he waited for his Baskervilles to reach the territory of Count Eyrie in order for them to break the final Sealing Stone. Rufus still retained his snarky attitude as he spoke with Oswald, however he did not talk down to Oswald, something which Rufus doesn't do with many other individuals.
Following Gilbert's betrayal and escape after rescuing Oz from his execution by Oswald's hands, Rufus revealed himself to Oswald, Lottie and the remaining Baskervilles, having hid behind a pillar during the ensuing chaos. Rufus' reasoning for not having joined in the defence against Raven and Gilbert's attack was that he and Dodo were still very strained from their encounter with Mad Hatter's powers after Xerxes Break had used it to escape Dodo's clutches. Rufus asked why Oswald did not simply use Bernard Nightray's Key to the Abyss to stop the flow of Abyssal power that fueled Gilbert's contract with Raven, as it had been formed using the Nightrays' Door to the Abyss, when Oswald didn't respond, Rufus mocked Oswald by mentioning how it appeared as though Oswald hadn't done as such.
Oswald explained to Rufus how the Baskervilles used to be the only one who had been able to form contracts with Chains, and any others who had done so were given a time limit before they'd be cast into the Abyss, thereby retaining order. Oswald then drew Elliot Nightray's sword and held it to the neck of Rufus as he continued to explain that the idiots of Pandora had created a loophole to allow regular people to form contracts with Chains. This shows that Oswald has been growing impatient with Rufus, and in the given situation he has no tolerance for Rufus' attitude.