As awesome as Kieren is, he deals with really shitty self esteem. His feeling that he deserves the guilt of killing people is semi-normal for the trauma he’s faced, but he also has to deal with the fact that he hates what he is. He can’t look at himself in the mirror, can’t imagine anyone liking him in the state that he is. But I think those reactions are, if not reasonable, at least expected from someone in his position with his mental health issues. He has residual fears, too, from the way the locals treated him even before he was PDS. Memories of the things that cut him to the core and drove him to the edge. Yet again, this is at least slightly expected considering the result of that bullying from the townspeople.
But Kieren doesn’t even think he’s worth his parents wanting to see him. He thinks they’ll hate him because he’s a zombie that killed people. He thinks that because of what he is, his family shouldn’t want to see him or talk to him. And when he gets home, he’s surprised that he was even missed. He’s surprised that his parents actually kept his room. He honestly thought no one would care if that he died and everyone would be better off and just go on with their lives without him as if he was never there. That he should just be easily replaced.
And after everything, he cannot bring himself to believe that he’s not a burden to his family in this state. He can’t bring himself to believe that they’re not just housing him because they have to and that they aren’t just tolerating him. He can’t believe they’d still want him around as a PDS sufferer, as someone who brought them so much pain and worry because of his mental illness and his death and his new state as a PDS sufferer. He still thinks they wouldn’t care if he left, that everyone would be better off if he left. That he’s worthless the way he is. He hates himself and what he is and I don’t think he can see any of the things that others see in him except the shit the townspeople say about him. He cannot believe that his family would want him to stay. He can’t fathom anyone liking him and wanting him around when all he sees is a worthless guilty monster.