well i think there is a line that you have to draw. i freak out if my roommate borrows my pencil without asking, but things like the iron, or microwave or vaccuum were hard for me to share at first without being asked, but I realized that they were things my roommate absolutely NEEDED to use. Sure you NEED a pencil sometimes... . because it is on YOUR desk i would want him to ask, normal household common items, i would lay off about. I am not sure how to get across to him what he needs to ask for and what he doesn't. But I do think you are flirtin with the line of being a control freak, and not being one. My roommate used to ask if she could use anything, and the things I wanted her to ask for I would answer "yes" and then things like the vaccuum I would say "yeah, you don't have to ask about that." Good luck!