Steve wakes up in the morning with permanent marker on his palm. It simply says: Come to the bathtub. Time to plan Operation: El Dorado. In hindsight, trying to put together a strategy to woo Bucky was never going to work while Tony was naked and in the bathtub.
(In which Tony does whatever the hell he wants, but it works out anyway).
Steve's jaw drops. Inside the chest cavity of the Iron Man suit a gorgeous fluffy black Ragdoll cat with a perfect circle of white fur on his chest stares up at them with an expression of pure irritation.
“Ah. He is not lost to us then.” Thor says, smiling down at their fluffy new friend.
“Mustache markings.” Bucky says faintly, drawing Steve's attention to the white spots of color that do indeed form a tiny mustache on the cat's face.
“Tony?” Steve whispers. The cat meows in a way that can only be described as miserable.
When Steve goes into a rut while he and Tony are kidnapped by Hydra, Tony is convinced that what happens between them is going to ruin everything. He's wrong.
Bucky Barnes is unwillingly dragged along when Nick Fury goes to talk to Tony Stark about the Avenger Initiative, as a little demonstration of the bigger universe Tony's just joined.
Tony Stark receives an invitation to Steve and Bucky's wedding. He has absolutely no idea who they are. For their chutzpah, he decides to pay for everything for their wedding- and hop into the planning to make sure they get the best of the best.