I warned you not to pull on that thread,” Natasha said, but there was no satisfaction in her tone. She rested her hand on Steve’s shoulder as he stared through the one-way glass at the… thing that his friend had become.
Bucky’s skin was sallow, his fingernails long and sharp as claws. He prowled the featureless confines of his prison, testing every seam and surface that the magic-inscribed chain around his ankle would let him reach. More disturbing than any of that was the corner-to-corner black of his eyes, glowing dully red deep in the pupils.
“He’s still in there,” Steve said after a long moment.
Natasha sighed. “He may retain some of Bucky’s memories, but they hold no meaning for him. He’ll probably use them to try to manipulate you, but you have to know, Steve, that he’s not really Bucky any more.”
“I won’t give up hope,” Steve said firmly. “There’s got to be some way to fix it. To bring him back. Surely you know something that can help.”
“There are tales of vampires who are able to regain their souls,” Natasha said. “But they’re only tales, Steve, the dreams and wishes of loved ones left behind.”
Steve finally turned to look at her. “Vampires are only tales, too,” he said, quiet and fierce. “Find out whatever you can.”
“Where is he?” Bucky demanded, before Steve even fully entered the room. The vampire lunged at him, hands like claws swiping through the air. Steve prudently stayed well back, behind the line painted on the floor that defined the limits of Bucky’s reach.
Bucky hit the end of his chain so hard he stumbled and nearly fell. “He’s here somewhere,” he snarled, whirling away to pace like a caged animal. Only a few days into the Avengers’ custody, and he was pale – well, paler – and gaunt. “I can smell him! What have you done with him?”
“Who?” Steve asked.
Bucky sneered. “The Stark boy, of course.”
“Tony?” Steve said without thinking. “How do you know Tony?”
“My masters had their uses for him, over the years. Too much his father’s son to join us willingly, of course, but an unknowing dupe can be led down a lot of useful paths, given the right handling. If you can keep him alive long enough, of course.”
Steve leveled a flat look at his once-friend. “I want to help you, Bucky, but if you’re going to threaten my teammates–”
Bucky glared right back. “If I’d been trying to kill him, he’d be dead,” he snapped. “My detail was protection. Do you know how many assassination attempts on him I foiled before he even reached thirty?” He scowled and turned back to his pacing. “Until Stane turned on us. He almost succeeded. Haven’t seen the boy since, but he’s here, I can feel him. Bring him to me.”
“I’m not bringing you anyone until we’ve cured you,” Steve said firmly. “I brought you something to eat.” He set the insulated bag on the floor and pushed it across the line into Bucky’s reach with the toe of his boot.
Suspiciously, Bucky took the bag and peered inside. “Pah!” He snatched out one of the bags of blood and brandished it angrily. “Fine brandy and tender steak in my nostrils, and you offer me this dog food?”
“Steve,” Natasha warned through his earpiece, already knowing Steve’s response.
Steve ignored her. “If you need it fresh, Buck, you can have some of mine.” He started to roll up his sleeve, ignoring Natasha’s cursing.
But Bucky just turned away. “Not yours. His.”
Steve paused. “Tony’s?”
“Wanted him from the first moment I got a whiff,” Bucky confirmed. “They promised I could have him, when he was no longer useful.” He dropped the blood disdainfully, flopped down onto his narrow cot, and turned his back to Steve.
“…and it’s been how long since he last ate?” Strange asked, stroking his mustache. Steve wasn’t sure he knew he was doing it, but if Steve wasn’t so worried, it would’ve been cartoonish and funny, like a villain from an old movie reel.
“Not since we captured him, at least,” Natasha answered. “He turned down bags from the bloodbank flat. Won’t even look at them. And Mr. Poor Life Choices here–”
“Hey!” Steve protested.
“–offered him an arm,” Natasha continued without even glancing Steve’s way. “But he wouldn’t take that, either.”
Strange had stopped stroking his facial hair, and looked faintly alarmed. “It’s been nearly a month since you asked for my help containing him,” he said, suddenly stern and grave.
“We all know how time works, Amazing Mumbo,” Tony said, not looking up from the tablet he was doodling on, probably to antagonize Strange. It never worked – Strange seemed merely amused by Tony’s belligerence – but he kept trying. “This isn’t the prehistoric age or anything.”
“Actually,” Clint said, “a lot of what we consider prehistoric civilizations had fairly sophisticated timekeeping systems. There’s archaeological evidence that– What? Look, my weapon dates back to the paleolithic, and I like documentaries.”
“The point is,” Strange said, “if he goes much longer without feeding, he will enter a semicomatose state of torpor.”
“That doesn’t sound too bad,” Clint opined, ignoring the dirty look Steve shot him.
“The torpor itself is fairly benign, yes,” Strange explained in that supercilious lecturing tone that always made Steve sympathize, just a bit, with Tony’s urge to irritate the sorcerer. “But when he eventually emerges from it, the need for blood will drive him into a mindless state of ravenous violence, with strength and speed several times what they are now. I have never heard of this frenzied state subsiding before dozens, if not hundreds, have been slaughtered. For his sake, as much as your own, I urge you to avoid it.”
“I’m open to suggestions,” Steve said drily. “Are we supposed to pin him down and force-feed him? We’ve tried everything we can think of that falls even close to the line of sanity. He keeps insisting the only blood he’ll take is Tony’s.”
Tony looked up. He scrubbed a hand over his face. “Let’s give it to him, then.”
“Tony, we’ve been over this before,” Steve said. “The risks–”
“I’m not talking about walking in there and letting him gnaw on me, Cap,” Tony said. “I’ll just donate a pint to the cause. In the interest of keeping him from going Freddie Krueger on us.”
Steve didn’t like it, but he couldn’t think of any other solution, not until they’d found a cure for the vampirism. He sighed. “Anyone else have any other suggestions?” he asked, not really hoping.
“I suggest we start with a smaller sample,” Bruce said. “Half a pint, maybe even less, just to make sure he’ll take it.”
“Yeah,” Tony agreed, not looking much happier with the situation than Steve felt. “Let’s call his bluff before we install a tapline in my veins.”
“We’re not installing a–” Steve gritted his teeth and got a grip on his temper. “Fine. Let’s do it, see how it goes.”
Somehow, Bucky knew as soon as Steve came in. He didn’t sneer or taunt Steve at the sight of the half-full blood bag. Instead, he reached out for it desperately, the sullen red glow flaring to life deep in those obsidian eyes, like a coal suddenly given air. “Give it to me,” he said, and it was closer to a plea than a demand. “I need him.”
Steve surrendered the bag without argument, and Bucky fell to his knees, fangs already sinking into the plastic. He let out a moan that under any other circumstances would have been obscene, and then a throaty groan that couldn’t have been anything but obscene. Steve fought down a blush.
As Bucky drained the last drops from the bag, he whimpered and folded in on himself, then let the empty bag drop to the floor. He whined and then panted in what sounded like pain.
“Bucky? You okay?” Steve leaned closer, panic fluttering in his chest, only remembering to stay behind the line of safety at Natasha’s warning in his ear. “Buck?”
Bucky looked up at him. “Steve,” he whispered, “Stevie, it ain’t enough, it won’t last.”
“What won’t last?” Steve asked, and then realized that the red glow was gone from Bucky’s eyes, and the black was slowly receding into the pupil where it belonged, revealing the steel-grey Steve remembered so well. “Bucky?”
“It’s me, Stevie, it’s me, I swear,” Bucky gasped. “No, don’t!” he barked when Steve started to step over the line toward him.
Steve froze, but it was agony. “Buck–”
“Ain’t safe. It’s going to come back,” Bucky said. “I can, can feel it, already, closing in.”
“You have to fight it,” Steve said. “Fight it off, Buck!”
“I can’t,” Bucky said, and his expression twisted in agony. “As soon as that bit of blood gets burned off… It’s something in the blood, in him, Stevie. God, everything I’ve done… I can feel the anger. He hates me, doesn’t he?” His eyes swiveled toward the opaque glass that hid the others in the observation room, his mouth twisting in agony. “There’s no forgiveness for what I’ve done.”
“No, Buck. You protected him, remember? That’s what you said.”
Bucky grimaced. “At their command, to further their ends. Who would forgive that? Why didn’t I just die?” He looked back at Steve, desperate. “Why didn’t you just kill me?”
“You know I couldn’t do that, not as long as there was any hope at all,” Steve said, aching.
“Oh, God, I can feel it closing in,” Bucky whimpered. He put his hands over his face and shivered. “Don’t let it take me, Stevie. Kill me before I can hurt anyone else. Please! Promise you’ll kill me!”
“No,” Steve choked. “No, I could never. We’ll find a way, Buck. I promise you that. We’ll find a way.”
Bucky shuddered violently and then went still. After a moment, he held out a hand, wordlessly begging Steve to take it.
“Don’t,” Natasha said sharply in his ear. “Don’t cross the line, Steve. He’s gone again.”
Steve nodded, and kept his hands at his sides. “I know.”
Bucky gave up the ruse and looked at him, hatred plain in his coal-black eyes. Steve left the secure cell and went back out to the observation room, where Natasha and Tony were watching. “He’s still in there,” Steve told them triumphantly. “There’s hope.”
“Maybe,” Natasha allowed. “Be careful, though. He might still be playing you.”
“But his eyes, and–” Steve broke off, because Tony, uncharacteristically, hadn’t said a word. He was still standing in front of the one-way glass, watching Bucky pace, his expression thoughtful. “Tony?”
Tony jolted a little, as if the sound of his name had pulled him from thoughts a thousand miles away. “What? Oh, right, yeah. He looks better, doesn’t he? I guess we’ve got a reprieve from the whole mass massacre thing, then.”
“Captain Rogers,” JARVIS said, jolting Steve from sleep, louder and more sharply than Steve had ever heard him before. He sounded almost alarmed. “You are needed most urgently.”
Steve rolled out of his bed, snatching up the shield as he came to his feet in response to the AI’s urgency. “Talk to me.”
“Mr. Barnes’ room, Captain,” JARVIS said, sounding ever more flustered. “Quickly, please.”
Oh, god, if that taste of Tony’s blood had given Bucky the strength to free himself from Strange’s restraints– Steve ran. “Tell Tony to put on the suit!” he barked, mind racing. The armor would slow Bucky down a little, at least. He burst through the door into the stairwell and vaulted the rail, swinging down two stories at a time, three.
“I’m afraid that won’t be possible, Captain,” JARVIS said, voice vibrating oddly as it bounced from speaker to speaker, chasing Steve’s progress through the building. “Mr. Stark is already with Mr. Barnes.”
“He’s what?” Steve hadn’t thought he could move any faster, but somehow he managed it.
He slammed through the door into the observation room. It was dark in Bucky’s room, but there was just enough light for him to see– Tony was curled in Bucky’s lap, the fall of Bucky’s hair hiding Bucky’s mouth where it was undoubtedly latched onto Tony’s neck. Steve yanked at the door to the cell. His fingers left dents in the metal, but the door resisted him. “JARVIS!” he shouted. “Get this damn door open!”
“Working, sir,” JARVIS said, sounding oddly breathless. “The codes have been changed.”
Steve turned to the one-way glass. It was strong stuff, developed originally to contain the Hulk, but Steve swung at it with the shield anyway. It didn’t even chip.
Bucky and Tony must have heard the impact, but neither man reacted. Steve could see now that Tony’s arms were wrapped around Bucky, a gross parody of a lovers’ embrace. Steve slammed into the window again. “Tony! Bucky!”
“Bozhe moy,” Natasha said, coming in behind him. “What was Tony thinking?”
“I’m afraid I don’t know,” JARVIS said. “Captain, the door, now, please.”
There was a soft click and a hiss as the airlock pressure-seal released, and Steve all but yanked it out of the frame. “Bucky, stop!” He charged into the room, ignoring the boundary line entirely. He stumbled to a halt when Bucky’s head lifted, red pupils glowing obscenely in the dim light. Blood – Tony’s blood – dripped from his chin. “What have you done?”
Bucky laughed, and did not answer.
Tony shifted in Bucky’s grasp, grimacing in pain as he turned to look at Steve. “Cap,” he said, voice sluggish. “You weren’t… weren’t s'posed ta… not until…” His arms flexed and tightened as he cautiously pulled himself a little more upright, though he didn’t let go of Bucky at all. “Gotta trust me, Cap,” he slurred. “Gonna… gonna be…” His head dropped onto Bucky’s shoulder, and Bucky laughed harder.
“Blood calls to blood, Captain,” Bucky mocked. His burning-coal eyes shifted to Natasha, standing now in the doorway. “Didn’t your precious research tell you–” He broke off with a gasp, eyes widening in shock. “What–?”
Tony grunted and jerked awake. He squinted up at Bucky’s face and grinned sloppily. “Knew it,” he rasped. He tipped his head back to expose the wounds in his neck, still oozing blood. “Come on, have another little sip,” he taunted.
Bucky growled and shoved Tony off his lap. “What have you done to me?” he snarled. He stood, looming threateningly over Tony’s limp body, but a split second later collapsed to the floor himself, curled tightly and howling in pain.
Steve darted forward and pulled Tony back, away from the writhing vampire. “Tony. What did you do? Did you… take something? Damn it, we’re supposed to be helping him! What did you–”
“I am,” Tony mumbled, batting ineffectually at Steve’s hands. “Didn’ take anything bad. Some… coagulants. So I wouldn’ bleed out while…” He waved weakly at Bucky.
Natasha came up and began briskly and efficiently cleaning Tony’s neck, applying careful pressure to slow the flow. “I don’t understand,” she said. Tony’s eyes closed, and she snapped her fingers in his ear until his eyelids dragged open again. “Focus, Tony. You need to explain this to us. What’s happening?”
Tony shrugged with one shoulder. He looked over as Bucky let out a particularly piercing cry, then turned back to Natasha. “Could hear ‘im in my head. Earlier. While he was… back. Went away, after the vampire took over again. Wanted to hear it again. I figured, little bit of blood fought it off for a while. Maybe more would. Would eliminate the… the infection.”
“Tony,” Steve said, fighting for his voice through warring terror and hope. “What do you mean, you heard him in your head? And one friend for another, that’s… That’s not a trade I’m willing to make!”
“I know,” Tony sighed. He lost the battle to keep his eyes open, sagging against Natasha’s shoulder. Bucky had fallen silent, and Tony’s tired voice sounded loud in the sudden quiet. “Knew you wouldn’t… Took the coagulants, try to slow the bleeding.”
“Hearing someone’s voice,” Natasha said before Steve could respond, “that’s… that’s soulmate stuff.”
“Mm,” Tony agreed, not moving.
“Are you saying your blood can cure Bucky because you’re soulmates?” Steve demanded.
Tony lifted a hand in a weak thumbs-up. Steve looked back at Bucky, who was beginning to stir. “Buck?”
“Steve? That you? Stevie, I feel awful.” Bucky lifted his head, and his eyes were human again, showing white behind the pale blue irises. They rounded in shock and fear when they saw Tony cradled in Natasha’s arms. “Tony! Oh, god, I didn’t– What did I do?” He started to reach out, then snatched his hand back and scurred away, as far from Tony as he could get. He huddled against the wall, shaking. “No, god no,” he whispered. “Please. Tony. Please.”
Natasha gathered Tony closer and stood. Tony wasn’t a light man, but Natasha managed to lift him. She carried him across the room, toward Bucky.
As soon as Bucky realized where she was going, he began shaking his head violently, but when she stood before him, he uncurled and reached out, almost helplessly, to take Tony from Natasha’s arms. “He’s alive,” she said softly, “just… drained.” She smirked at her own joke, then brushed back a messy curl of Tony’s hair with a tenderness she would certainly deny later. “He’ll heal faster if he has direct contact with his soulmate.”
Bucky’s eyes widened, and he looked up at Steve, even as he clutched Tony closer. “Soulmate?” he breathed.
Even mostly unconscious, Tony seemed to be drawn to Bucky, curling into Bucky’s chest and slipping an arm around his waist. Cautiously, Steve let hope begin to overtake terror. “Yeah, Buck,” he whispered in a voice hoarse with sudden tears. “That seems just about right.” He crouched beside Natasha to rest a hand on Bucky’s shoulder. “How are you feeling?”
Bucky chewed his lip, considering. “I feel… clean,” he said, breathy with awe. A smile tugged at his lips – not the vampire’s malevolent smirk, but something wholly Bucky, bright and hopeful, if not entirely carefree. “I think it’s gone, Steve.” He brushed a thumb across Tony’s jaw. “I think… I think he brought me back for good.”
Natasha stood. “You two will need to stay in close contact for a few days, until the bond is fully formed,” she said thoughtfully. “I’ll go rouse Bruce and send him down to help Tony, and then call Doctor Strange.”
“Right,” Steve said. He stood slowly, reluctant to leave Bucky’s side but feeling the guilty pull of duty. “I guess I’ll–”
“You stay here,” Natasha said. “Obviously, someone needs to keep an eye on these two troublemakers.”
“Hey now,” Bucky protested. “You don’t even know me, when I’m under my own power!”
Steve snorted, and Natasha laughed. “You think I haven’t heard any stories? Besides, you’re Tony Stark’s soulmate.”
Bucky buried his face in Tony’s hair, but Steve could see the blush crawling across his neck. “Yeah, I am,” he admitted.