Concilliabule: Clint & Natasha
For a month, everyone thinks Clint and Natasha are fucking. They disappear into locked rooms, exchange glances that no one else can decipher, and most moments will find them standing together with heads bowed, speaking intently.
The theory gets complicated when Steve starts to join them.
It isn't until a rare quiet evening, when everyone is summoned to the common area, that the purpose of the secrecy becomes clear. Natasha is wrapped in a trailing red cape, while Clint is wearing a tin-foil replica of Thor's helmet, and Steve holds up a massive Mjolnir-shaped cake. Over their heads is a hand-painted banner that reads "Happy Earthiversary".
"It's been a year since you starting living full-time on Earth," Natasha explains to a baffled and beaming Thor.
Clint grins and adds, "We figured that was worth marking."
Thor hugs them so hard it pops Steve's back, and the party goes on well into the night.
Tony still thinks Clint and Natasha are fucking, and Pepper just pats him gently on the shoulder and tells him to shut up.