The first time it happened they were drunk, or at least Bucky and Natasha were.
They'd had a fight about it, actually -- they could have those now; Bucky was well enough, clear enough of his recent past, that they could fight again. They'd had a fight because Tony had offhandedly suggested they find out if whatever Schmidt did to Bucky had the same effect on Steve -- if Bucky could get drunk. Or catch diseases, but getting drunk seemed easier. Steve had winced at his lack of tact, but Bucky liked Tony, and he'd just laughed.
"You're on," he'd said, and Steve couldn't just leave Bucky at the hands of Tony Stark, so Bucky won the "should we go drinking" fight by default and Steve went out with them to keep an eye on them. Natasha went too, because Bucky found her reassuring and because she and Steve were testing out this whole "boyfriend-girlfriend" situation, something neither of them had done before.
At least, not without using false names, in Natasha's case.
So they took one of Tony's cars to a dive bar where Tony wore sunglasses inside so as not to be recognized (did not work) and Steve sulked and caught up on reading mission reports on his phone while Natasha and Bucky drank Tony under the table.
"Are you feeling anything?" Tony slurred, as Steve and Bucky dragged him out to the car, Natasha following with the bottle of tequila she'd won off a fool who thought he could compete in a drinking competition with a Russian, a supersoldier, and a Stark.
"Sure," Bucky told him, as he slung Stark in the back of the car and followed him in.
"On a scale of one to me -- "
"Okay. Imma make a note of that," Stark said, and passed out.
Steve, having lifted his keys about six drinks earlier, climbed into the driver's seat. Natasha climbed in over him, settling next to him on the bench seat (Tony did have excellent taste in cars). Steve wasn't about to complain as she tucked herself under his arm.
"You look happy," she said, not even slurring or unsteady.
"I am happy," he replied, as he guided the car through the sparse late-night traffic. "I never expected -- " he glanced in the rearview mirror.
"Just say it," Bucky groaned.
"I never expected to have my best friend back. Or a best girl at all," he added, kissing her forehead.
"You only get away with calling me that because you're cute. And old," she told him.
"I'm sorry. My favorite woman," he corrected.
"Not feelin' awkward at all back here, cuddling with Stark while you two make wet eyes at each other," Bucky said.
"It's about time I got to be the one to make wet eyes with a girl, you did enough of it when I was still a little guy."
"I could take you," Bucky threatened.
"Don't bother," Steve said. "We'll be home soon and I don't want to crash Stark's car."
"Drop me at HQ?"
"Why are you still living there?" Natasha asked, twisting around. "Stay at the Tower tonight."
"I'm still not -- "
"You're safe, Buck," Steve said, over Bucky's dying protest. He caught Bucky's uncertain look in the rearview mirror and held his eyes. He knew Bucky had them lock him in, at HQ. "You're safe. Nothing's gonna happen, but if it did, I'm bigger'n you and I won't let you hurt anyone."
Bucky's face fell, a combination of shame and gratitude, and Steve felt the pained twist of it.
"Besides, HQ's out of the way and I'm amazed the two of you haven't gotta pee like crazy, all the drinking you did," he added.
There was a sudden uncomfortable silence in the car. Steve stepped on the gas.
Tony was awake by the time they reached the Tower, so Steve just made sure he got inside the penthouse before heading down to Natasha's apartment.
Mostly, these days, they shared her place. It had been a source of rare comfort, in the days when Bucky was being deprogrammed, to curl up with her and let the world go damn itself for a while. She wanted to be in her own place; Steve just wanted to be with her, and she didn't seem to mind, so by the time Bucky was well Steve was there three or four nights a week. It felt fast to him, but then an affair with Natasha Romanoff was never going to be normal. He wouldn't have wanted normal, not after all he'd seen and done.
When he arrived, they didn't notice him; there was music playing, and he was silent by habit, silent enough that even Bucky's enhanced hearing and Natasha's natural alertness didn't pick up his footfalls.
The music coming over the speakers wasn't what he thought of as his, swing and jazz; it was some pop song he was pretty sure was recent. They were dancing regardless, Bucky swinging Natasha around the room in a clumsy, no-actual-steps trot of some kind. She was keeping up more out of the classical dance training she pretended she didn't have than from any understanding of what he was doing. Steve leaned in the doorway and watched, amused, applauding when the song ended. They jerked apart sharply.
"Come dance," Bucky said, after a few awkward seconds. "Come on, man, have you danced yet? At all?"
"Metaphorically," Steve drawled, stepping into the room. "Not literally. Nobody dances like they used to anymore."
"Yeah, you get to make up your own steps now," Bucky said, as the next song on the track came on, a slower number. He stepped away, as if making room for Steve to take Natasha's hand, but Steve grinned and caught him around the waist with one arm, grabbing his hand with the other, just so damn happy to have him back. Bucky laughed nervously as Steve swayed him; the metal of his left hand was warm, but his fingers twitched, as if he wasn't comfortable with someone holding it. His whole body was warm and heavy, a little awkward, a little reluctant. When Steve glanced at Natasha, she was watching with an interested look on her face.
She caught his look, raised an eyebrow, and looked pointedly at Bucky. Steve nodded. After all, the three of them were connected -- soldiers in enough wars to make them understand which rules just weren't that important.
"Nah, come on, you got a beautiful lady right there -- " Bucky said, just before Natasha grabbed his chin and Steve held him still so she could kiss him. When she leaned back, Bucky's eyes went to Steve.
"Look, we're both drunk, but you got better sense than -- " he began, and Steve grabbed Natasha's hand as he bent and kissed Bucky quiet.
"Live a little," he said, against Bucky's mouth. "Make up your own steps, Buck."
It felt like it took hours to reach the bedroom, though it probably wasn't all that long. Bucky had to be coaxed, step by step, one or the other of them kissing him the whole way. Natasha, with more presence of mind than Steve had in the face of pending sex with his oldest friend, had them half-undressed by the time Steve pushed Bucky onto the bed.
"I hope you got some choreography in mind," Bucky said, as Steve shucked his pants and Natasha crawled onto the bed, sitting on Bucky's hips decisively.
"Why? You're good at improvising," Steve said, as Bucky sat up to kiss her. Steve gave Natasha a gentle shove, more of a suggestion than a push, and she toppled onto her side, pulling Bucky with her. Steve slotted in behind him, tugging Bucky's t-shirt over his head backwards, ripping it when he didn't move his left arm fast enough.
The two of them had been together in the years Steve slept silently by, and they fit well. While they relearned each other he nuzzled Bucky's shoulders, leaving kisses from the bicep of his right arm to the seam where his left shoulder ended in metal, stopping only when Bucky's shoulders tensed. Steve made a note in his head -- don't get too close to the arm yet. Buck was sensitive about it, skittish when people approached him from the left, as if the arm might act independently of him. He returned to the nape of Bucky's neck, the surprisingly soft skin there. He could feel Natasha's foot catch his calf where her leg was flung over Bucky's hip.
Steve wasn't any particular adept at sex, and he didn't have fancy tastes. He was content to skim his hands along their bodies, bury his face in the crook of Bucky's neck, and give him a little leverage when he was inside Natasha, something to push against. He didn't need much else, just liked touching. He got his hand between them and petted Natasha until she came, drawing a satisfied noise from Bucky as well, but then felt his hand shoved away from Bucky's cock (oh god, Bucky, naked in his bed, he'd been trying not to think about the fulfillment of an adolescent fantasy for so long) and Bucky turned, kissing him.
"Didn't think you swung this way," Bucky said, cupping his ass with one hand, pulling them together.
"For you," Steve murmured. "Never was another man for me, Buck."
Bucky groaned and pressed his forehead to Steve's cheek, breath hitching, and then went tense and still.
"Buck?" Steve asked. Natasha's face appeared over Bucky's shoulder, looking mischievous.
"Did I ever tell you much about James and me?" she asked. Bucky was sucking in air like he was drowning. "He used to love this."
"This?" Steve asked, bewildered.
"Takin' it in the ass, Steve, Jesus Christ," Bucky managed, and Steve blinked.
"Oh -- Oh!" he breathed, pushing himself up on an elbow to see better. Bucky moaned and gripped his hip. Natasha was -- "Oh, wow."
"Distract him," she ordered, and Steve nodded obediently, dropping back down while Bucky huffed and groaned and twitched in his arms.
"Hey Buck, hey, you like it though, don't you?" Steve asked, worriedly, tucking their heads together, one arm over Bucky's shoulder to cup the back of his head. "We don't have'ta."
"Are you kiddin' me," Bucky gasped. "Get you in me and me in her and we'll have a hell of a time."
"Done that before?" Steve asked with a grin.
"Done this before," Bucky replied, gesturing at Natasha. "Plus I got a great imagination and I've seen movies."
Steve kissed him and let Natasha take care of the rest, until finally Bucky said "For the love of God, I'm ready, come on," and Natasha slapped him loudly on the ass. Steve felt the rush of cold as Bucky withdrew, and watched with wonder as Natasha lay back, Bucky kneeling over her until her thighs wrapped around his hips.
"Come on, Steve, don't make me spell it out," Bucky said, and Steve rolled to his knees, uncertain what came next. Bucky leaned over, sliding effortlessly into Natasha, and then spread his knees wide and --
Steve reached out to touch him, almost disbelieving, thumb coming away slick. Bucky huffed.
"Be patient," Natasha chided, fingernails digging into Bucky's shoulders. Steve set his jaw, reminded himself that this was probably the least complicated thing he'd worked out about the modern world, and eased in slowly. Every time Bucky's breath hitched, he stopped -- and once or twice because he was gonna go off if he wasn't careful -- and that seemed to work okay, even if he could see Natasha rolling her eyes.
Finally, though, Bucky exhaled and said, "You can move, you know," Steve withdrew and thrust carefully, and felt it -- felt it roll through Bucky, heard Natasha's inhale sharply.
Bucky was slick and warm, tight but -- yielding, moving with Steve, bowing his will to the rhythm Steve set, and that was the headiest part of it. Buck was a stubborn bastard, as stubborn as Steve and in some ways less willing to bend, but here he was. Obedient. Quiet except for an occasional gasp, body lax for Steve's command. Natasha was never terribly loud, but she was louder than Bucky, urging them both on, moaning and crying out -- close to coming again, he could tell, and Bucky was trembling, panting --
Natasha came, muscles tensing, a thin cry cut off sharply, and Steve felt Bucky's orgasm roll through him like a physical shock, so hard he wrapped an arm around his waist just in case he fell. Bucky's body tightened around him and set off rockets behind Steve's eyes, a belly-deep spark that drew him up tight and then let go all at once.
He felt Bucky dip forward and drew out of the haze of orgasm long enough to make sure they didn't tumble right on top of Natasha; they landed together on their sides, next to her, and she burst out laughing right as Steve pulled out and Bucky yelped in surprise.
"Nice dismount," Bucky growled, elbowing Steve in the ribs, not that hard.
"Well, next time, warn a fella," Steve said. "Phew. That was something else."
"Thanks, I think."
"Hush, he means well," Natasha put in, and Steve opened his arm so they could sandwich Bucky between them, and he could rest a hand on her hip. "Sleep, James."
"Not tired," Bucky muttered sleepily.
"Tough nuts," Steve said into his hair. "I'm sleepin'."
Bucky squirmed a little, but he was out before Steve was; Steve caught Natasha's eye over the edge of Bucky's cheek, grinned, and gave another nod.
It was good. A night with his best friend, giving Bucky something he clearly wanted. And he trusted, in the morning, they'd all still be friends. They were too crazy to be anything else.
Bucky didn't even remember much the next morning, and he made a joke out of it, and Steve told himself that was a good thing.
"Walkin' a little funny," he said, hitching his hips as he sat down for breakfast. "Guess it was fun regardless."
Steve smiled over the fruit he was slicing into his cereal. "I enjoyed it."
"Feels like it," Bucky said, leering, and that was the last they talked about it.
Until it happened again, three months later.
Steve hadn't intended it to happen again. It had just been for fun, a drunken fumble. Even with Bucky living at the Tower now, in Steve's guest room because Steve was hardly there and Buck never did get used to having much space to spread out in -- even seeing Bucky daily, and loving him with a depth that scared him sometimes, he hadn't expected a repeat performance.
But there'd been an Avengers call out, and Bucky was still benched, which meant that when Steve and Natasha came back to the tower after the debrief, hurting and exhausted, Bucky was full of kinetic energy from having to watch and worry, helplessly, while they fought.
"For Pete's sake," Steve finally said, after the third time Bucky got up to get more coffee. He grabbed him by the arm (flesh arm; Bucky was still touchy with the left) and pulling him down across his body. Bucky's ass landed up between them, legs on Steve's lap, shoulders on Natasha's breasts where she sat sideways on the couch.
"What gives!" Bucky yelled, and Natasha clamped a hand around his neck, the other arm going around his waist.
"Settle," she hissed, and Bucky, to Steve's surprise, went limp.
"I was worried," he said sullenly, turning his head. Natasha kissed his forehead, which turned into a kiss on the lips, which somehow turned into the three of them squirming around with each other, clothing half-still-on, bruised and dirty and frantically fucking with hands and mouths and whatever else they could. Steve got come all over his Captain America pants, which was mortifying, and Natasha pulled two stitches, which was worrying, and Bucky told them the next morning, before he was awake enough to remember it later, that it was the first good night's sleep he'd had since last time.
Natasha, cradled between the two men this time, looked up at Steve, and he looked down, and she nodded.
After that it only took two weeks to happen again (a movie night for the three of them with a movie carefully chosen for a specific sex scene), and that time Bucky just stayed all day and they did it again the following night.
Two days after that they had dinner and Bucky stayed; Steve liked that one, the one where they gave Natasha a peep show. The following week, Bucky showed up at Natasha's door with beer and microwave popcorn, and for the first time, he started things.
It was just comfort. It was fun. Bucky liked sex and clearly wasn't getting as much as he used to, so why not? No reason for anyone to be jealous; he was Steve's oldest friend and Natasha's ex, so they had deeper connections than who kissed who the most. And if it helped Bucky to sleep, so much the better. Steve wanted to care for him. God knew Bucky had done enough of that for him in their lives together.
It was good. It was casual and helpful and good.
At least, until it happened three times in a week and when Steve woke up after the third time, Bucky wasn't there for breakfast. He didn't answer Steve's text about getting lunch, and he wasn't around when Steve went looking, though JARVIS said he was fine. The strangeness of the absence, of the sudden distance, made him fret. All the more when it stretched on for days; Bucky would at least respond to his texts and he saw him sometimes, but he was "busy" -- distant, inattentive, slow to reply.
"Hey, I got a modern-day question for you," he said to Natasha one evening. She was sitting with her legs over his, doing her nails, testing out something new Stark had invented -- metal alloys suspended in nail polish, that could be applied to the edges of the nail and then sharpened on a whetstone.
Stark hadn't thought this all the way through, Steve felt, but then he wasn't the one sleeping with her.
"Did someone try to make you like Guns'n'Roses again?" she asked.
"No. It's -- I'm not really up on this kind of thing, etiquette-wise. But I think...how many times a week can a couple have a threesome with the same guy before it becomes some kind of three-way relationship?"
She set the bottle aside. "He's frightened."
"Because we're dating him."
"Because he wants us to be," she said.
"Do you want us to be?" he asked.
"Coward. Admit, then ask," she replied.
"I'm not a coward, I'm deferring to -- "
"That makes me a chauvinist, not a coward," Steve said. She gave him a dry look.
"He was yours first," she said softly.
"He wasn't mine, we weren't ever..."
"He was yours first, Steve. You know this is true."
"But I was yours first," Steve said, studying his hands, wrapped around her knees.
"I was your first. That's not the same thing."
"I love you," he blurted. She went very still. He knew she would; he'd never said it before and she'd never asked for it. They were both afraid of it but it couldn't go unsaid now. "I do and I don't need -- we ain't missing anything, you and me."
"So you don't."
"But we're more with him. We're all right without him. We're better with. And he needs us."
She was quiet for a while.
"Let me deal with this," she said finally. "Let me speak to him."
"To keep him, or to let him down?" he asked, carefully hiding the pain at the latter idea.
"To see what he really wants," she said. "Trust me?"
"Of course," he replied, but he slept in his own bed that night.
He could just barely, if he strained, hear Bucky's breathing on the other side of the wall.
He wasn't sure what to do with himself, without Buck around as much and without any certainty about what Natasha was up to. He worked out (usually Bucky was in the gym with him) and went out for a walk in the city (usually Natasha would go along and they'd end up getting smoothies somewhere) and finally, by the time dinner came around, he gave up and admitted he was a bad person and went to find Natasha.
This time there was no music playing, but they still didn't hear him; Bucky was lying on the couch with his head on Natasha's lap, right hand lifted to play with the tips of her hair, the two of them in what seemed like serious conference.
"...missed you," he was saying. "He missed you, the -- the Soldier. But I missed you too."
"I'm right here, James. I'm not going anywhere."
"You're with Steve now, though. That's better. I never treated you right."
"You gave me what I needed to survive. And more," she said, catching his metal fingers and kissing them carefully. He pulled them away, visibly changing the subject.
"Shacking up with Steve, that shows some great taste, you know. I mean, you're out ahead of every other girl he ever tried to impress."
Natasha's smile was fond. "Thank you."
"I love him," Bucky continued. Steve could feel his heart break for Buck -- it had been so much harder for him, so much worse. "He was always the better half'a me."
"Trying to live up to Steve can be difficult," Natasha said, fingers threading through Bucky's hair soothingly. A quick stab of hurt passed when she added, "He doesn't want us to, though. He loves us for what we are."
"Yes, James, you should know that," she said, and Bucky lifted her hand to his mouth this time, kissing it.
Steve was inside the room before he'd thought about it, and he reached the couch before Bucky was fully off it, fear rising in his eyes.
"We were just," Bucky began, but Steve dropped to his knees and caught Bucky's face in his hands, kissing him, probably less gently than he ought to have. He didn't know how else to explain. He didn't know how to talk about this kind of thing, or how to tell another man he wasn't the best part of anything, just another part.
"Shut up, you dumb fuck," Steve said, pressing their foreheads together. "How could you think I -- I don't want you to be anything but what you are -- "
"But I'm not -- "
"Shut up, Jesus Christ," Steve insisted, holding Bucky still. "I'm sorry, Nat, I shouldn't have come up, it's not that I don't trust you -- "
"You got restless," she said, in a not-entirely-placated tone of voice.
"Somethin' like that," Steve replied. Bucky began to shake, and Steve wrapped his arms around his shoulders. He felt Natasha's fingers smooth his hair.
"I had things under control," she said. "I had a plan, you know."
"Yeah," Steve murmured. "Sorry."
She sighed. "Well, what else am I supposed to do with the two of you?"
"Keep us," Steve suggested, still a little daring; for all he knew she'd been about to let Bucky go from this -- this arrangement they had.
"You really are idiots. That was always the plan," she replied.
Bucky pulled away from Steve, head whipping around. Steve saw her smile. Bucky looked back at him, and he shrugged.
"I never claimed I was in charge of the relationship," he said. They both looked at Natasha, who looked unusually pleased with herself.
"Don't the two of you make a nice matched pair for me," she said. "It's not about us keeping you, James."
"Coulda fooled me," Bucky said faintly.
"Probably; you always did fall for my line," she said, and Steve caught at least a hint of a smile on Bucky's face. "It's about the three of us keeping each other."
Bucky looked down. "Not much good at keeping people," he said.
"I don't know," Steve replied. "You came back for me. Looked after my best girl before I got there," he added, with a teasing grin at Natasha, who gave him a supremely unimpressed look. "Bucky," he added, lifting the other man's chin with his hand. "Don't you want us? We want you."
"I want lots'a things I'm not liable to get," Bucky said.
"Then you should keep hold of what you can," Steve replied. He let Bucky go, because Natasha was pulling him against her, and Bucky went reluctantly, the fingers of his left arm flexing and releasing repeatedly, clicking a little as they did so. Steve stood and held out a hand to Natasha, who took it and pulled herself and Bucky up gracefully.
"We can keep on as we have," she said, as Steve pulled Bucky into a backwards embrace, arms around his waist, chin resting on his shoulder. "Or we can learn some new steps. You're a good dancer, James. This is up to you."
Bucky was silent, and they waited; finally he said, very quietly, "Yes."
Steve's heart heaved in his chest and before he'd really worked out what to do he found himself lifting Bucky off his feet, laughing, and twisting away from Natasha to carry the flailing man to the bedroom.
"HEY. Leave a fella some dignity!" Bucky protested, as Steve backed him through the doorway and essentially threw him onto the bed, going back for Natasha, who was right behind him anyway. He spun her, twirling her through the door, and then fell onto the bed between her and Bucky, which was one of his favorite places to be anyway.
"You know what I'm looking forward to?" Steve asked, drawing his legs up to pull off his socks. Natasha crawled over him and started to work on Bucky's shirt. "Telling Tony. I bet his eyes get really big."
"Telling -- " Bucky said, then huffed as the shirt was pulled over his head. "Telling people, we're telling people now?"
"Well, sure," Steve replied, sliding one hand under the waistband of Natasha's pants and using the other to help her get Bucky's belt off. "I mean, everyone knows about Natasha and me."
"But -- this isn't, you know," Bucky said, as his pants came off.
"Normal?" Natasha asked derisively, rolling on top of him with her back to his chest so she could pull her pants off. Steve went to work on her bra. "Pfft."
Steve rolled his hips against Bucky's, wriggling closer, and kissed him roughly. "Tomorrow morning," he said. "I'll tell the world."
"Hey, now, we don't gotta -- " Bucky began, then hissed as Natasha raked her fingernails down his shoulders.
"Maybe not the world," she said, patting one of Steve's cheeks with her other hand.
"Engraved letters," Steve replied, rolling her into the bed and kissing her stomach. "Fancy as hell. Gold-edged and everything."
He pretended not to listen as she laughed, busy spreading her wide so he could nuzzle into her, licking at her clit, letting her and Bucky discuss between breathy moans what a weirdo they were dating. Eventually he felt Bucky's hand in his hair, pulling him up and away, and he fell into their arms happily, contentment lapping under his skin.
As a boy he'd been perpetually worried that he and Bucky would be separated one day -- get married, fall away from each other, not be Steve'n'Buck anymore. Or more likely, Bucky would find a swell girl and Steve would be the Sunday-dinner uncle, if he lived so long.
They had been separated -- first by the war and then by death, a long sleep for Steve, a fractured existence for Bucky. The fact that they had come back together was a miracle, and that Natasha had loved each of them, been there for each of them, felt like a blessing he hadn't looked for or deserved. He kissed her, wrapping a hand around Bucky's against his stomach, warm skin against warm metal, and closed his eyes.
He heard Bucky laugh low and felt Natasha's hands, and tried to freeze the moment in his mind forever.
Steve woke, the next morning, to find Bucky gone from the bed; he was on his side with one arm thrown over Natasha's bare back, her head buried in the pillow, but the blankets on the other side of her were empty of a body. Steve frowned, unhappiness filling him. He'd thought they were clear, but perhaps Buck hadn't understood -- or worse, perhaps he'd decided he didn't want them the way they wanted him. Maybe they'd moved too fast, pushed too far --
There was a crash, and Natasha was up and off the bed in an instant, gun in one hand; Steve, rolling to the other side, ducked well out of its way and then ran for the bedroom door. The crash had come from the kitchen…
"God dammit, Natasha!" Bucky yelled, as Steve reached the door. He heard the click of her gun being set on the bedside table. "I know you have a samovar! Where are you hiding it?"
"Ugh, men," Natasha muttered, brushing past Steve, pulling a shirt (his shirt) on. "How I wound up with two of you is a mystery. James! Put the frying pan down, what are you thinking?"
"I was thinking I'd make fried eggs and real coffee," Bucky said, as Steve strolled into the kitchen behind her. "But your booby-trapped cupboards woke half the people in the building, and you have no eggs. I might just eat pie."
"You eat pie with your hands, whole slices with your hands like an animal!" Natasha said.
"That's why it has a crust!"
Natasha said something tart in Russian, and Bucky looked appalled and retorted "Wash your mouth out!" and Steve sat down at the kitchen table to watch, amused, as the pair of them attempted to make breakfast.