Demon Dean (Proverbs 17:3)

Dean Winchester is a Knight of Hell that exists in an alternate universe.

Early History
Some point in the past, Dean became bearer of the Mark of Cain and it corrupted him into a Knight of Hell.

Season 15
In Proverbs 17:3, due to the shared wound between God and Sam, Sam sees a glimpse of this alternate universe, where Dean savagely attacks his own brother before killing him with the First Blade.

Appearances

 * Season 15
 * Proverbs 17:3