I think my roommate is creepy
Why do you think he is creepy?
He frequently stares at me and watches what I do all day even though I don't talk to him at all.
I understand what you think your roommate is creepy. Maybe it's just how they are and you should try to communicate with them that it makes you feel little bit uncomfortable.
I'm thinking of writing a diary so that he can read how much I hate him. I'm going to get back at him.
I wouldn't recommend doing that, that would make more issues down the line in my opinion. Like I said simple communication could get this resolved pretty quickly.