Looking for a fic in which the boys are choosing their angel mates, or are being chosen, Dean is chosen by Gabriel and they mate quickly and successfully, Sam is chosen by Cas, and it takes a while for him to get into Cas, and to feel like it is a good match. Meanwhile, Dean seems genuinely happy with Gabe. Wings change color after mating is one big detail which might make it stand out (maybe?) also: wings enclose the couple during mating, and Deans is sort of public in the very beginning.

Thank you!