Work Text:
Bucky knows that Steve has a long-standing “being fucked or fucking a robot” fetish. He knows from seeing him draw himself & robots in various sexual positions. So when he meets Iron Man for the first time, he pulls Steve aside as soon as possible to ask him if they’ve fucked yet. Steve says no, but admits his fetish is as strong as ever and he’s over the moon for Iron Man, but he thinks if he’s fucking anyone, it’s Tony, who made him. Bucky considers that as possibly true, but admits the inventor has caught his eye, so maybe if he had someone else that would free up Iron Man for Steve. In the mean time, Steve takes an interest in Bucky’s metal arm. They used to fool around growing up, so Bucky falls into the old habit, jacking Steve off with his metal arm as he fucks Steve’s ass.
Later, Bucky is doing reconnaissance on Tony and wooing him. He ends up finding out Tony likes a bit of force, and that he easily goes into subspace. While in subspace, Bucky asks Tony questions about Iron Man like “Have you ever had sex with Iron Man?” (“No”) “Could Iron Man have sex?” (A pause. “He could probably adapt to that.” A puzzled look “Do you want to have sex with Iron Man?” Bucky reassures him with a kiss that no, he is quite satisfied with the inventor.) Later, Tony is fully clothed but in subspace with Bucky {I like the idea of Tony in a tuxedo, because Bucky is getting his head cleared before a gala or something, or after as a reward for not getting drunk.} and they come upon Steve in the hall. Steve is concerned about Tony “is he drunk?” “No, quite the opposite. He’s been a good boy so he’s being rewarded.” Tony smiles as Bucky kisses him. “I wanted to let you know, Steve, Iron Man is free to have sex with you if he’s open to it. Tony doesn’t have any objections or lay any claim to monogamy with him.” Steve beams, thanking both Bucky and Tony, assuring them both that he’ll ask Iron Man about it next time he sees him. Tony watches Steve walk away with a puzzle trying to break through the fog of subspace. But then Bucky has pulled him against the wall and Tony decides it can clearly wait until later.
Later…
Tony is suited up as Iron Man. Steve asks him if he’s ever thought about sex with a man before. Iron Man answers yes, that it seems enjoyable. Steve is very excited and asks if he would jack him off. Tony remembers what Bucky said about Iron Man & Steve and agrees.
Meanwhile, Tony still has a sexual relationship with Bucky, but as Iron Man he’s with Steve. Steve and Bucky are also still in their old habits, fucking behind closed doors, often talking about Tony and Iron Man and how fucking good they are for their kinks. (Steve & Bucky are a lot more vanilla.)
At some point Steve mentions wanting to be fucked by Iron Man, so Tony makes a specialized armor with a metal dick. Steve loves it. Steve happens to mention that he wishes Iron Man could get as much out of it as he was. (At this point it becomes important that Tony is female bodied.) With that in mind, Tony alters the armor to “provide a self-lubricating fuckhole.” (It also sucks on his clit whenever in skin-to-skin contact.) Steve remarks “It seems so real, and feels so wet” as he fucks Iron Man for hours. Iron Man sleeps with him that night for the first time.
Bucky hasn’t seen Tony since yesterday, and looks everywhere for him. Eventually he runs into Steve instead, who distracts him telling him all about fucking Iron Man the night before. Having missed his nightly dose of Tony, Bucky gets easily aroused and takes it out on Steve. But it’s not too into it before they simultaneous realization that stops them in their tracks. Are they cheating on their partners (Iron Man and Tony)?
They decide to find Tony first. Tony is in his lab. “What’s up darlings?” he asks, internally convinced that they’re going to break up with him, but trying to hide it.
Bucky speaks first “Tony, I uh, have a confession to make. I didn’t really intend to keep it a secret, it just kind of happened. Steve & I have been fucking like we have since we were boys. I hope you can forgive me and allow me to continue my relationship with you, and Steve.”
Steve then speaks “You make Bucky incredibly happy, and I don’t want to get in the way of that at all. I would never want to take Bucky away from you.”
Tony’s face gives nothing away as his mind works through what they’ve just said. They’re fucking, which he knew, but they’re confessing it like they were cheating? Is this another part of the game?
Tony hedged “So, you two have been having sex behind my back. Do you want me to punish you for it? That’s not really my thing. I knew you two were together before, and figured you still were. Just no stealing, now that I’ve had you, I want to keep you.”
Bucky lets out a relieved breath. “Thank you.” He kisses Tony’s hand. “And that won’t be a problem, you’re stuck with me now.” He winks at Tony.
Steve then says “I’m so glad for you, Buck. Now we just have to find Iron Man. Tony, do you know where we could find him?”
Tony looks at Steve like a deer in headlights as a realization hits him. They don’t know that he’s Iron Man.
Tony almost starts to laugh manically, but they wouldn’t understand. And this seems like the time for coming clean doesn’t it?
“Tony, what’s wrong?”
“It’s probably easier to show you.” Tony goes over to a console and engages the SX-69 protocol, engaging the privacy protections of the lab and revealing the armor he specially designed for having sex with Steve. Tony had wanted to see if there was a way to let Steve use his mouth too, but now he wondered if he’d ever get to.
(I don’t know how much proof they both end up needing, but eventually they accept that Tony & Iron Man are the same person.)
Bucky licks his lips as he seems to be tightly reining in his anger “So you’ve been Steve’s fuck robot for the past few weeks?”
“Yes,” Tony admits.
“I kept you for hours, Tony.” Steve admits, seeming almost horrified with himself.
Tony looks sheepish “I actually really enjoyed that, Steve. I designed the armor so I would be comfortable being fucked or fucking for hours. My entire existence just to please you sexually.”
Tony flinched at how fast Bucky crossed the room. Bucky pressed himself to Tony’s side, and Tony felt that it wasn’t anger Bucky had trouble restraining right now. His pants were similarly struggling. “You liked being a sex toy whose only purpose was to get him off, did you slut?” His hands started to roam Tony’s body, his mouth breathing hot in Tony’s hair. Tony nodded “That’s so fucking hot,” and with that he kissed Tony.