So I was going to give this 3 stars because there are rather a lot of errors in it but then I remembered that this is a 'oneshot only' fic and I can't write a tweet without errors so actually this is really fucking impressive.
Fluffy, fluff, fluff, fluff and adorable because of it. Derek is a librarian. I can't even with how much I love the idea of that. Jesus Derek in a library. Derek surrounded by books. It's almost breaking my brain just thinking about it.
I'd really like a follow up to this.