I think the scene involving razor blades and Cas' face would count ... it's a fairly long fic and a lot of other stuff happens .

Graceless by cheesewith
http://archiveofourown.org/works/823760?view_adult=true

Summary With the angels cast from Heaven, the big question is obviously how to get them back. The task is far from simple and the addition of old enemies claiming to be new allies only muddies the water. The fact that even their best plan promises dreadful consequences doesn't help.