Howdy!  Only one I have in the castle is Quincy Smellie ( the library's near resident excited bundle of energy that is trying to read his way into being a wizard ).  If he isn't in class, exploring the castle, or at a Slytherin Quidditch practice/game decent odds he is in the library or somewhere with one of it's books trying to make magic work ( to this point he is batting a zero on actual spellwork so the books/library are safe ).  Though it would be reasonable to be concerned about his tendency to twiddle his wand in his hand while concentrating and reading books in a way that occasionally slips into being out loud.