sibling drama

i keep telling myself i shouldnt bother but my younger bro keeps stealing my stuff like its not a big deal, one day he took my favorite watch and now im just paranoid everything im wearing will disappear next. i caught him red handed once with some of my clothes on and it was so weird seeing myself in his hands. he says hes sorry but i dont know why he cant leave me alone, is it really that hard to ask? its not like i have a ton either but sometimes im just tired