Yet none of it struck him quite as much as the sensation that there was someone or something else in that grim room, both unseen and present, and coming for him as much as for anybody.
Death. Earlier it talks about how he's been in this school since he was six months old, and he'd never experienced local life before because he was so sheltered. He's never taken public transportation and has only met a few locals in his life. Also the narrator keeps bringing up the human mysteries of the world, which makes me think this kid doesn't know a lot about the real world and now after experiencing death for the first time he feels this feeling that he and everyone else'll die one day, but he's still new to the whole reality thing, so he's not exactly sure of what it is thats "coming for him as much as for anybody"