Obsession is the forty-fourth chapter of the Vampire Knight manga.
Kaname Kuran walks away from the council building contemplatively. Blood tendrils follow him. He talks to Rido, saying how they are alike, talking about an attachment that refuses to disappear even when there is no hope.
Zero Kiryu begins to feel the pressure and his gun starts to feel heavy. He reiterates his desire to end it all, but he hesitates because of his attachment to Yuki Kuran. Scenes of Yuki's past expressions go through his mind. He struggles to ignore them. Zero's memories continue from previous flashbacks in chapter 12.
Yuki holds Zero's arm and comforts him after she finds him clawing at his neck, asking him not to hurt himself. Zero wonders why she is crying and finds it annoying. He acquiesces to Yuki's request, but mentally decides to simply hide it from her next time.
Zero's sleep is troubled. He's calling out his brother's name before awakening with a start. He has an annoyed expression on his face as he calls out to Yuki. He asks her to tell him how long she plans to stay outside his door, and tells her to return to her room. Yuki's footsteps are heard rushing back to her room and she slams her door shut. A few minutes later her footsteps are heard again and she opens Zero's door. She apologies for entering, but expresses concern that she could hear him not sleeping well, she asks if she can come in. Zero sits up and tells her she is free to enter because its her house and thinks about how he doesn't care about anything. Zero turns back to sleep, his mind can only focus is holding on and not losing his sanity. He holds his face in his arms when Yuki places her hand on his head to her surprise. He looks at her from the corner of his eye, she promises to stay there like that until he falls asleep. She sits on the bed beside him, telling Zero how she also once had troubles with her sleep and thanks to a certain someone with very gentle hands patting her on the head, she could fall asleep. Zero turns to look at her, his cynicism is gone from his expression. She tells him it will be ok and he starts to fall asleep, focusing on the warmth of her hands, how they kept him from sinking, he tells her she doesn't have to call him "~kun" anymore.
Yuki is patted on the head by the gentle hands she spoke of. She has a happy smile upon her face. She tugs Kaname by the arm mentioning something she wanted to tell him. Zero gets a shock as he realises the newcomer is a pureblood vampire and that Yuki is in love with him.
Zero reminds Yuki that he doesn't want her to touch him with hands that touched Kaname. Yuki stands at the door with new bandages, she apologises and asks him to change his bandages. He snaps at her and tells her to leave. He wonders why he is so angry. He begins changing his bandage while wondering if its because another pureblood turned up in front of him, or if its because Kaname might have been the one who taught Yuki to be so kind and gentle, his third thought is interrupted when he notices that though he normally heals fast, the speed at which he heals now is vampire like, he scratches at his neck again and punches the mirror. Yuki comes in concerned, she calls his name but he ignores her. His hand is bloodied as he leans into the broken mirror. Yuki tells him to stop and pulls his arm off the mirror, noticing his cuts. He yanks his arm away from her, yelling at her not to touch him. Yuki holds her hand, blood dripping from a cut she received from embedded glass in his hand. Zero stares at her wide-eyed. His heart beats loudly as he watches the blood. He puts his face in his hand as he asks Yuki to get the chairman for him.
Later Zero is carrying out the mirror, he leans his head against the mirror again, thinking about what happened when he saw her blood. He had felt thirsty, realises that her blood smelled different from his or Kaname's, her blood had smelled good to him. He faced the reality that he was no longer a human. The Chairman calls his name, Zero tells him he needs to become stronger so that he will not lose to the vampires...or himself.
Zero watches Yuki at the dining table, leaning on the table with her head resting in her arms sleeping. She wakens realising she fell asleep. Zero thinks she doesn't get enough sleep, because instead she comes to take care of him every night. Yuki asks if he is ok. He apologises for her hand. She tells him it was nothing and not to worry about it. She tells him she is happy that he is calmer now and lets slip that he scared her a little. He apologises, his eyes sadder now. Yuki is silent for a moment and looks away, she tells him not to be sorry and apologises and explains about the vampire who attacked her long ago. Zero tries to tell her he is a vampire too and his words fade away. Yuki tells him she realised that he must have lived through some scary things too related to vampires and that he mustn't want to hear anything from her, who is close to one. In his mind he vehemently denies that, but verbally does not respond. Yuki tries to take his hand, he roughly pulls his hand away and tells her not to touch him, thinking that he will eventually become a scary vampire like the one she remembers. Yuki looks sad. She lunges for him, he yells at her not to touch him, but she pulls him into a hug. He realises he is scared. Yuki tells him it will be ok, that if he has a safe place he can go, then he will be ok even when scary things happen, so he doesn't have to be afraid any longer.
Flashback of Zero's bite as he thinks about the day he dreads arriving. He remembers Yuki pledging to be on his side, while hugging him. He finds the arms that he has no right to seek, keep him from leaving, reflecting that he feels so safe in her arms its almost cruel. Yuki's gaze, unwavering and sincere, it always gives him strength.
Zero back to the present still points the gun at her and she holds her Artemis. Yuki still holds the same sincere and unwavering gaze upon him. He looks away and grits his teeth, asking why she doesn't move. He yells that he wouldn't mind if she killed him here. He sees Ichiru in his mind, telling him to live on and fulfil his goal. The chapter leaves Zero's thoughts unfinished as he begins to wonder something about the both of them.