Steve decides that he has to rescue Tony before he collapses from sleep deprivation due to a five-night engineering binge working on his repulsors/Clint’s exploding arrows/Nat’s stingers/Bucky’s new arm/something Fury yelled at him to do for SHIELD. Steve buys a bagel/doughnuts/cupcakes/sandwich during his morning run, freshens up as soon as he gets to the Tower, and wears a white, almost transparent t-shirt that shows off all his delicious muscles. Even though he’s still damp from the shower, Steve takes the elevator down to Tony’s workshop.
Dummy and Butterfingers chirp happily as soon as Steve arrives and he moves to pet them, then tosses them a ball as they scurry after it with tiny beeps of joy. JARVIS informs Steve that he just missed Tony awake ten minutes ago. Tony is hunched over his desk fast asleep, face smeared with oil/grease stains, tank top all rumpled, and hair all messy, but he is still the most beautiful man Steve has ever seen. Steve smiles to himself and sits on the couch/in his own Cap-designated corner with all his art tools to make a quick sketch of sleeping Tony. He’s already finished up five super secret Tony sketchpads. At first they’re just sketches of Tony in the armor, but recently the pages are full of Tony’s long, slender fingers/his smile/the curve of his back and ass.
Eventually Steve finishes his drawing and he lays a hand on Tony’s shoulder. Tony murmurs a little soft “Steve…” so the Captain chuckles to himself, scoops him up bridal style, and carries the genius back to his bedroom…counting on JARVIS to open the doors and to save all the work Tony has done.
It’s Avengers movie night. Nobody really knows how it became a thing, but it became a ritual for the Avengers, not just post-battle when they’re exhausted and just want to recuperate, but also when one of them is feeling lonely and needs the company. It’s the only time Bruce socializes away from his lab experiments/Clint goes down from the vents/Thor visits from Asgard/Tony and Pepper have time off SI/Steve is done working out in the gym/Peter and MJ are home from their date/Luke and Jessica bring down Dani/everyone is home from a mission. There’s popcorn and lots of yelling, and Steve and Thor deliberately ask silly questions about the modern world in the movies just to troll everyone.
Tony and Clint engage in a spirited debate about Star Wars versus Star Trek. Steve can feel Tony’s warmth beside him in their unofficial “Mom and Dad seat” and stares at him with a dopey grin on his face. He finally feels like he’s home in this brave new world.
He looks to his left and catches Natasha on the other side of the room sharpening her knives while giving him a Look. Because she just knows.
After a series of misunderstandings, Steve and/or Tony confess. They are both shocked. They had no idea. But they shrug it off, they may have confessed to each other, but it doesn’t mean that the other one is serious.
“I give you my blessing/you are good for him/I don’t care if you’re Captain America/Iron man, you hurt him and I will end you.” says Rhodey, Pepper, Bucky, Natasha, Sam, Carol, Bruce, and JARVIS.
Clint makes a joke out of everything but is secretly giddy. “LET US CELEBRATE THIS UNION BETWEEN SUPERHEROES!!!” booms Thor joyfully, and informs them that their bond is unique and sacred and has repercussions in the multiverse. Then Thor starts telling them about a universe where they’re all in highschool. Everybody is intrigued.
Tony knew all along that it couldn’t last forever. Steve marches inside the hospital room, furious blue eyes blazing, and Tony braces himself for the heartbreak.
Steve rips off his cowl and glares at Tony, complicated feelings of fear and love mixing with his anger. “How could you be such an idiot?! Why did you have to offer yourself to the enemy instead/stop your own heartbeat just to save me/jump in front of me to catch the bullet/lie to everyone just to be the villain and make the tough decisions so you can save us all?! You can’t do this to me, Tony. We’ve talked about this. I can’t lose you.”
“Captain America is more important than me–” Tony starts to insist, but Steve cuts him off with a desperate kiss. They kiss for a while, and then Tony pulls away, but he remains in Steve’s embrace.
“I love you, Tony. You gave me a home.” Steve says determinedly. “And someday, I’m going to go back in time and punch Howard in the face.”
“I love you too, but you can’t just say that so early in the story,” Tony whispers, out of breath. “I still have five more chapters left to pine after you and lie about my feelings and reflect about how useless I am and how unworthy I am of your love and basically do everything to sabotage our relationship. I am scum, Steve. Stay away from me.”
“I love you and we are going to fight for this. For us. Screw the plot, let’s skip all that nonsense.” Steve kisses him again.
“Language, Captain.” Tony manages to say between fevered kisses and promises, but he is smiling, heart warm with hope.
Stark Industries’ stocks dip a bit, then rise again. The public goes batshit over the announcement of their relationship. There’s even an official hashtag. The Avengers team grows, and movie nights are crowded. Steve and Tony start thinking about kids, until they decide for adoption/one magically appears because of somebody from Asgard/they try surrogacy/Peter Parker wants to join the Avengers/their kid from the future shows up. Everyone blames Reed for all the crossover fic.
In every universe, they fight for their love.