There is a fic, I think it might be a short series where Dean, Cas and Gabriel are in a three-way relationship and have a sort of bonding ceremony (Dean may gain wings because of it, I can't quite remember).  In a possible sequel/ later in the fic, Sam is feeling left out because of Dean's bond with the angels and slowly they incorporate him into the relationship.

I remember a lot of it seemed to take place in a hotel room.

It's a brilliant fic and I just can't seem to find it again. I would be extremely grateful if anyone could help.