Destiel’s soul/grace creates an angel baby- Fic FOUND
This is what I can recall from the fic. Dean has 2 sons in this fic, one of which is a human(maybe?). The other one was created by mixing Castiel’s grace and his soul, or something like that. The human kid is the older brother in the fic. I believe that Micheal was the one raising the angel baby.
The human kid didn’t get along with Dean in the beginning, he was kinda snarky. I think he mellowed out when he ended up getting his hands on the supernatural books. I’m also pretty sure that he was the result of a one-night stand that Dean had. I don’t remember much about their (Destiel’s) angel baby/Nephilim.
Gabriel and Lucifer were definitely in the story because they helped raise the angel baby. Balthazar was maybe involved, but that might just be wishful thinking. There might have been some Sam/Gabriel in the fic as well.
I think they settle down in a house somewhere.