First one he stole because he claimed it was his when it very clearly was not. I was about 15 or so (I think) and he's the older brother so...my stuff inevitably became his if he said so. After he subsequently lost that book a few years later, I let him borrow a second copy I got for myself. This book, in near pristine condition came back with pages torn and worn and the binding all sorts of broken. I'll still suggest books to him but I'll be damned if he touches another one of mine.
CS/CpE. Yay engineering!