After reading this pretty awesome fanfic I have a want to play Darcy/Howard Stark. It is a nice twist on Darcy being related to Tony but instead of being his daughter she is his mother. It comes about during Thor The Dark World due to Darcy ending up bouncing through a few portals and ending up in the past.
I would also be up for a pairing with Jarvis/Vision, Bucky, Natasha, or Bruce.