Talk:Ad Nauseam, Ad Mortem, Ad Infinitum/@comment-25678963-20141122212320/@comment-24101790-20141122214725

You are correct, the protagonist is able to see those three ghosts due to his connection with them. (Whether it is emotional or physical.)

He relates with the girl as he has just moved to a new place and is feeling isolated and lonely (Much like the girl). "I was beginning to see this nightly wraith as a friend and kindred spirit. She was alone and sad just like me." / "I would tell her how lonely I was, how desperate I was for someone to talk to." He unfortunately is reflecting his mindset on her. She may have killed herself for other reasons, but he is transferring/supplanting his mindset onto her actions and drawing a connection.

With his grandfather, he feels trapped by his situation. (His grandfather feels trapped by his illness and the protagonist feels trapped by his ability to see spirits.)

As for the little boy, that connection should be fairly apparent. (His guilt is a major catalyst for the conclusion.)