I think it’s fallen!cas (but it was way before season 9 and even before season 8)
I remember Dean is having a “gay panic”
Sam is awesome in this and try to calm him down and tells him to be nice with Castiel because Cas kinda lost his Dean (future!Dean) and he (past!Dean) act like a dick to him.
I remember that it’s really hard for Cas, he is hurt that Dean push him a away a lot.
I remember that Cas hide his ring a bit but not sure.
But finally Dean accept the thing and come to like this intimate relation with Castiel and yeah he admit he is in love with him.
I remember Sam and Castiel find a way to send him back in his time (and of course the future Dean is back to his time too) (or maybe it happen itself because there’s a lot of fic like that and I may mix things together sorry :p)
I’m sorry it’s blurred it’s been a great while and I think it’s well known fic but I searched for months and I can’t find it, please help?
Thank you very much !
Have a great day/night :)
Oh and it’s NOT :
The story of you and me : http://archiveofourown.org/works/985737/chapters/1942668
neither it is : The day the world went away: http://pyjamagurl.livejournal.com/166757.html (it’s similar and it’s a great fic btw I rec it to you guys!)