Specific Fic: Boyking!Sam and Demon!Dean

[lilafilly2]

Hello, I'm looking for a fic that

• season 4 au
• might have been part of a big bang because it had art attached to it
• was Gen (i'm 99% it was gen)
• and in which Sam and Dean figure out that if they kill Lilith before 65 seals are broken they can put permanent breaks on the apocalypse.

Ruby dies at some point, they summon her from a field or something. She sees his true face before she dies. I think Dean forced Sam to see himself in the mirror, maybe? Also, they succeed.