Actually the Weirdest Library Ever

You love libraries. The smell of old and new books. The people. The quiet. So, one summer, you decide to get an internship there. It starts pretty well. You recommend books, you put them on the shelves (and maybe have a little too much fun on the rolling ladder), and you help customers check out. Then one day, quite an odd customer comes in. You wouldn't have noticed him except that he radiates a powerful aura, and you notice that his eyes are bright red. You shrug it off and decide not to judge him, after all he would leave soon. But you can't help but notice that all the books he checks out have to do mythological creatures and legends - dragons, sea monsters, vampires, werewolves, fairies, and yes, even unicorns. You decide to let it go the first time, but as more and more odd customers come it, you decide to investigate - and fall into something more magical and way weirder than you'd ever imagined.