I just found a "book on tape" story among my saved podcasts where a demon takes over Dean at the same time Azazel kills Mary in Sam's nursery, assigning him to watch out for his chosen child. Dean doesn't fade away so easy, determined to protect his baby brother, and demon and Demon pretty much merge, both with the same goal, loving Sammy while still corrupting him for his future role as Boy King. I'd like to find any other stories where Dean doesn't leave the burning house the same innocent child, but still the loving big brother, even if now a demon.

pressed for time, bus is here -- back later with url for story