As Through a Glass and Darkly (http://archiveofourown.org/works/524025/chapters/927238) by lexicale: "Everything is the same, except for how it's different. Sam and Dean grow up with two mysterious guardians, a demon and an angel respectively, living in their shadows and preternaturally bound to them. They still move all around the country, saving people, hunting things. There's still an acceptance letter to Stanford and a family full of pain and anger. There's still an unbreakable bond of love and desperation between two brothers -- and there's still a man with yellow eyes with secrets enough to shatter the world. A re-write of Supernatural with Hindu mythology as its basis instead of Christian mythology."

If I remember correctly, the reincarnation in Non Timebo Mala (http://archiveofourown.org/works/273894/chapters/433454) is more suggested than explicitly stated, but it's still a great story: "This is my very AU version of the Colt's making. It's completely a child of my wild imaginings, thus expect anachronisms, improbable situations, and flagrant display of personal fanon. This can be seen as an alternate universe, or an alternate timeline."