I am sorry, but I have to pimp this. My weakness in fanfiction is a crossover. Harry Potter meets the Winchester brothers in Supernatural. Men in Black encounter the X-Men. Buffy the Vampire Slayer wonders how she ended up in Middle Earth. I am a sucker for a good crossover.
This fic,
"Cracked Stars Shining" by
azephirin is absolutely amazing. It features the pairing of my favourite character from the HP books, Hermione in manner in which I think she should have been written and the character, over whose picture I have drooled posted over the course of the past year or so, Dean Winchester. It is NC-17 so not really work-safe unless your boss is away.
The link is for the last part of the 12th chapter, but there is a link to the first part on the page.