The Library Troll
Remsis is the troll who tends the library. Reemis speaks slowly and acts sluggishly, but has a keen ability to see through student excuses, and a bulk that discourages any lies. Remsis does not appear to be educated herself, but knows the library like the back of her hand (or at least, she refuses to answer student questions about magic, always referring them to a book instead.)
She not only oversees the books, but also the loaning and sale of magic items. She has hefty fees, a collateral system, and authority to punish students who break the rules, in her own unique style.
Remsis has few friends and isn’t much of a conversationalist, but she treats others well who treat her things well.