Tony is flying overhead, helping Steve look for his long-lost, apparently-not-dead BFF Bucky, when he hears a wolf howl on the crowded Romanian street below.
That's when his spirit animal, a kea parrot whose vibrant plumage makes it look like it knocked over a rainbow and made off like a bandit, suddenly appears in front of his armored face, dives into the oblivious crowd, and lands on a giant, ghostly white wolf's shoulders.
Tony's never seen another person's spirit animal before. That privilege is reserved for a sentinel and their guide.
It's been more than a decade since he gave up on finding his sentinel—not that anyone knows he's a guide. He doesn't have the temperament. Sure, he has the empathy and uncanny ability to read people and a room well enough to sway even strangers, but he's not nurturing or calming or good at talking about feelings—unlike Sam, Steve's guide, who Steve found by trolling an innocent jogger on a random morning.
So unfair. Steve's only been a sentinel for about four waking years of his life, and less than two after he gets defrosted, he literally runs into his guide on a DC sidewalk.
Tony's been waiting forty years and seen neither hide nor hair of his sentinel—until now.
Tracking down his childhood crush can wait. He can help Steve after he finds his sentinel.
"Something's come up," Tony says through his HUD comm, doing an aerial about-face to follow the wolf that's now loping down the sidewalk. "I need to take care of it. Catch you later, Cap."
"Tony—" Steve starts, frustration evident.
"That's fine," Sam says, unruffled. "We'll call if we find him."
"Back at you," Tony says, then switches off his comms. "Where are you taking me?" he mutters, eyes fixed on the spirit animals leading him to his destiny/soulmate/whatever. Accounts differ on what, exactly, the sentinel–guide relationship is, but they all agree that when you meet them, you'll know, and it'll feel like the axis of your world has shifted from you to that person. Tony's not sure he's ready to make another person the center of his world—look how well that turned out with Pepper, for god's sake—but he can admit to himself that he's always wanted that depth of connection, that bone-deep knowing. Now, finally, it looks like he'll get it.
The translucent wolf walks through a closed door into what looks like a dingy apartment building. Tony lands and follows—opening the door, of course, because he can't choose to be incorporeal whenever it suits him. He's conspicuous in his bright red and gold Iron Man armor, but at least none of the gawkers are trying to stop him for selfies and autographs. He's sure he'd come off like a dick if someone got between him and a lifetime of banked hopes on the cusp of fulfillment.
He flies up the cramped stairwell instead of walking in his armored boots and causing a ruckus that might freak out his sentinel, who, depending on which of their senses are enhanced, would undoubtedly notice the unusual clanking at some point during the three-flight climb. The repulsors probably sound unusual too, but at least they're quieter.
When Tony emerges from the stairwell, the giant wolf is waiting for him, sitting in front of the nondescript door to apartment thirty-two. It's now, looking at the wolf head-on, that Tony confirms what he'd only suspected: the poor thing looks like it's been through the wringer—much like Tony's kea had while Tony was held captive in Afghanistan. The wolf's fur is dirty, uneven, and patchy in places; it looks on the thin side of barely healthy; and there's a mournful look in its slate-gray eyes that makes Tony want to take it home, cuddle it, and maybe feed it an entire deer and buy it a forest to run around in.
It figures Tony's nurture-y, guide-y instincts would kick in for a magic wolf harder than they've ever kicked in for a person. Tony's hit with the renewed worry that he'll be a terrible guide to whatever sentinel is unlucky enough to be stuck with him…but that won't stop him from meeting whoever's on the other side of that door.
When Tony lands and steps out of the armor ("Sentry mode," he tells JARVIS as the armor closes up behind him) to walk the last few steps to the door to his destined sentinel—future relationship status unknown—the wolf walks through it, Tony's kea still perched contentedly on its shoulders like a Lisa Frank sticker on an off-white sheet paper.
"Rude," Tony mutters. His kea could've waited for him, but no, it wants to see Tony's sentinel first. What a brat.
Tony would've walked through the door too, if he's honest. Instead, he's stuck knocking.
No footsteps sound before Tony hears the door unlock. It opens a sliver, revealing two lock chains, but nothing else. He hears a soft gasp on the other side—
And the door slams in his face.
Before his heart can plummet too far, or his thoughts spiral past "He knows I'm a shitty guide" to something worse, he hears a battery of locks and what sounds like heavy furniture moving on the other side of the door. It opens again, wide enough to see the man on the other side, and Tony meets slate-gray eyes matching those of the white wolf currently pressed to the man's legs and knows this is his sentinel. This is the one.
Shockingly, "You're Barnes," he blurts.
James "Bucky" Barnes is his sentinel—and this is indubitably him. His dark brown hair is longer than in Aunt Peggy and Dad's pictures, and his silhouette is hidden beneath several layers of shirts, a hoodie, and a leather jacket, but he's still arrestingly gorgeous, broad-shouldered and tall, with a jawline that could cut glass. The effects are devastating in person. More so, in fact, because he's Tony's sentinel.
Barnes looks like Tony feels: like the center of his world has leaped from himself to another man's heart. "You're mine," he says, pretty eyes wide and tenor voice thready with awe.
Tony's verklempt. "Um-hm," he agrees intelligently. To have his sentinel immediately claim him with such unfettered admiration is exhilarating. "Wow," he says when he gets his feet back under him. "Not what I was expecting. Not complaining, though. Definitely not complaining. Can I—"
"Come in," Barnes finishes with him and steps back enough for Tony to slip inside.
Briefly, Tony's eyes flit to his armor. "J, tell Steve I found him, but don't send our location. Tell him if he shows up before I give the all-clear, you've been ordered to open fire."
"Am I to open fire, Sir?" JARVIS asks through the armor's speakers, stepping closer to guard the door.
No, obviously, but before Tony can respond, Barnes glances between him and the armor, frowns, and says, "Steve found his guide, right?" At Tony's nod, Bucky tells JARVIS, "Tell him if he interrupts me learning mine, I'm gonna shoot him again. He knows why."
"I will do so, Sergeant Barnes."
'Mine' again. Tony can't help grinning stupidly when Barnes says it. He'd be lying if he said the idea of his sentinel—his sentinel!—getting all possessive right now isn't hot.
It's typical behavior of a sentinel who hasn't imprinted yet; Tony knows that. Upon meeting their guide, sentinels feel a strong biological drive to learn and map their guide with each of their enhanced senses. The imprint helps them shift focus to their guide when zoning, and more easily locate them if separated. Mapping one's guide is an intimate, literally sensual experience—albeit not always a sexual one.
Tony hopes this will be a sexual one. He doesn't know how many of Barnes's senses are enhanced, but what with the hungry look in his eyes, Tony's mind and dick are eager to find out.
It's a rush that Barnes is claiming him, even knowing the biology behind it. Bucky Barnes will ruthlessly guard their time together and chose it over reuniting with his long-lost best friend.
When Tony slides past Barnes into the apartment, a warm hand lands on his stomach, staying him and scattering butterflies low in his gut. While Barnes locks and locks and locks the door, Tony drags his eyes from his sentinel to look around.
Their spirit animals have vanished—no doubt wandered back to the spiritual plane Tony's seen in a handful of dreams now that they've brought him and Barnes together.
Even without a giant metaphysical wolf taking up floor space, the apartment feels cramped—and depressing, what with the sickly yellow wallpaper, dingy balcony door, and worn wooden floors mottled with stains. A small kitchen and surprisingly long, cheap-looking table take up half the main room. The twin bed opposite them spans much of the rest. There's a heavy-looking trunk against the wall by the front door—the furniture Tony heard moving from the hallway, he realizes, when Bucky drags it back into place to bar the door shut, revealing the marks it's gouged into the floorboards. Despite the bright afternoon sunlight and the windows' lack of blinds, the room is dim; not only is the overhead light weak, newspapers are taped over the window panes. The backlit newsprint adds a layer of "unhinged" to the feeble decor.
Given what Tony knows about Barnes's sordid history as a mindfucked programmable assassin, that should probably give him pause… But it doesn't. Tony knows he's safe. And if Barnes is anything like Steve is about Sam, he'll move heaven and earth to ensure Tony stays that way.
"I know who you are," Barnes says, watching Tony in his peripheral vision, "and you know who I am. Call me Bucky. What should I call you?"
Mine is good—Tony liked that one—but "Tony" is what he says.
Bucky cocks his head like he's heard something fascinating. When he turns from the door to study Tony with shrewd eyes, he's got an unfairly attractive smirk on his face. "That's not what you wanted to say, is it?"
Tony's surprised and then delighted—if slightly embarrassed—to have been caught. "I do want you to call me Tony, but you're right. That wasn't the first thing that popped into my head."
Bucky drops his hand from Tony's stomach, but then the metal one Tony's been dying to see up close gently wraps around his wrist and pulls him further into the room. "What popped up first?" Bucky asks, stroking Tony's wrist with a slightly cool metal thumb. His pupils are wide, and hunger has returned to his expression. "You liked that one." His tone and grin are flirtatious, challenging.
Tony is many things, but shy is not one of them. He's also more comfortable voicing some thoughts during foreplay and sex than in less intimate contexts. So he readily admits, "I did." And because Bucky is lighting him up like precious little has since his amicable breakup with Pepper more than a year ago, he can't resist impishly adding, "Completely your fault, by the way. It's the first thing you called me."
Bucky's eyes narrow briefly, then widen in recognition. He pulls Tony close and cradles his neck with a warm, careful hand, thumb light as a butterfly against his pulse, and adroit fingers tangled in the curls at his nape. Tony shivers in anticipation. "Mine," Bucky murmurs, voice soft but intense, like the look in his eyes as he studies Tony's reaction.
He must feel how Tony's heart beat faster to hear that; hear the click in his throat when he sucked in a breath; see the barely-there flush of his ears heating and the smile he can't hold back. Mine, Bucky said like an immutable fact of the universe: fire is hot; water is wet; Hammertech sucks; Tony Stark is mine.
Bucky's pleased grin is small, warm, possessive. "You want something to drink first, or can we start?"
Tony pretends to think about it, but his hands betray him by pushing under Bucky's many layers to rest against his bare waist. "Depends. How many senses are we imprinting?"
Bucky's grin sharpens. "Five."
"Fuck." Tony's brain may short-circuit, just a little, just for a moment. Bucky is going to study his body, commit him to memory, with all five sentinel-grade senses—and likely the thorough attention that made him so flawless an assassin that for seventy years the intelligence community thought him a myth.
It's standard for a sentinel to coax as many reactions from their guide as possible during imprinting. They want to catalog their guide, collect as wide a data set as possible.
Sex is the most efficient way to do that—and the most fun, and the method they both clearly want to use.
Tony is especially looking forward to touch and taste. His dick throbs. Want courses through him, sending tingles down his spine and settling in his ass and balls. He knows sex is the method, not the goal, and that his least attractive features will probably get stared at, and he'll be sniffed in weird places, listened to long enough to be maddening, and touched and licked literally everywhere regardless of the state of his dick—he'll be a fucked-out mess long before and after he comes—but that's okay. "I'm ready for my close-up, Mr. Barnes," he purrs semi-facetiously. More seriously, "Do whatever you need to do."
Bucky releases Tony's wrist to slide his metal hand down Tony's back, cup his ass, and squeeze. "What about what I want to do?"
Tony's mouth falls into an open-mouthed grin, and he sucks in sharply, hips jerking. "Fuck. That too."
"God, look at you," Bucky croons, syrupy sweet, voice heady with admiration. "You're perfect, aren't you, baby?"
He strokes Tony's cheek with his thumb, and his eyes flit across Tony's face like he's drinking in every reaction: how Tony stills, breathless, before leaning into his touch; the heat on his face; his eyelids dipping with pleasure at Bucky's praise before he wills them to stay open.
"Already being so good for me," Bucky murmurs, seemingly to himself.
He sounds pleased, even proud, with nary a hint of disappointment, and it sends a shockwave of heat through Tony's chest that radiates outward. His tremble is impossible to miss.
"So good," Bucky says, then leans down and kisses him slow, like he's savoring the taste of Tony's lips, and then deeper, fucking his tongue into Tony's mouth and sweeping through it, systematically mapping its contents—and probably catching the phantom taste of the coffee Tony drank on the QuinJet. The kiss is wet and messy and loud. Tony thinks it might be the hottest thing that's ever happened to him.
And he knows Bucky's only getting started.