<human>: Can you provide a brief rundown of the text in within 3 sentences?

My parents recently took in a roommate, Vince. He sounded shady to me from the beginning, and I discovered he did drugs, which I disapproved of. I read a lot of books, and he wasn't able to take his to my home with him, so I offered him the use of mine. 

I went to my grandmother's for a few days, and when I returned I saw someone had been really snooping in my room. As in, looking under cushions and attempting to get into a locked box where I keep my old journals. I was miffed, but figured it was my father looking for something. Then I went to read one of my books and saw it and several others were missing. I asked for the one I immediately noticed back, and he had it, so I am assuming he has the others, which are library books. I don't understand why he didn't ask me beforehand or tell my parents he was going to look for a book to read. I should mention that all my books are in large piles on my desk; he'd be an idiot not to notice them, so there was so reason to search my cushions. 

We'd had a few rows before (I'd politely told him that if he wanted to smoke, he had to do it outside, and he got snippy). I want to get along with this guy, but I don't think this is called for. I told my parents and they were angry at him but don't like confronting him about anything he does that they don't like, including the drug use, smoking, etc. How can I politely tell him he should ask if I'm reading something before taking my things, and is there any tactful way of asking why the fuck he was snooping through my very uninteresting bedroom?
<bot>: New flatmate takes books and snoops through bedroom. I want to be nice about it, but I want it to stop. My parents are useless.  Help please?