“You’re sure?” Tony asked, coming up behind Steve where he knelt on the bed.
Steve nodded. “Yes, absolutely.”
“Okay then, here goes,” Tony muttered and slipped the collar around Steve’s neck, a small click audible when he pressed the ends together. Steve’s breath stuttered, and his cock—already rigid and straining—grew even harder. He wrapped a hand around the base of his dick just to be sure he wouldn’t lose control, and then lifted his hands to explore the collar.
It was thick, about two inches high and while he could probably tear it free if he had to, there was no way to remove without breaking it until Tony released it. Right now, it fit snugly, and it didn’t take much to imagine how easily it could tighten around his throat.
“And you are certain this is safe?” Thor asked, tone doubtful as he also touched the collar.
“As safe as something like this can get. I control how tight the collar gets,” Tony waved the small remote he was holding in his hand, “but there’s a small bio-monitor built in, so JARVIS can keep track. If anything goes wrong, he’ll release and unlock it.” Tony stepped back, settled himself in the plush armchair set a few feet from the bed.
“Not going to join us?” Steve asked. Normally Tony wouldn’t miss a chance at sex, so him choosing to sit out was odd.
“Not for this. One of us needs to needs to monitor.”
“I’ll be fine, Tony,” Steve said, rolling his eyes.
“And me being over here will make sure of that. This isn’t up for debate, Steve, and if you want this, you need to accept that.”
“Fine. Next time?”
“We’ll see. Safeword?”
“Skylight.” They’d all decided there was no way any of them would utter that during sex.
“Okay. I’m all set.”
“All right.” Steve turned back to Thor, already naked, sitting up against the pillows. Sliding up the bed, Steve knelt over Thor’s legs and leaned down to kiss him. Thor stopped him with one broad hand in the center of his chest.
Worried blue eyes looked into his as Thor moved his hand to gently cup Steve’s face. “You are sure about this, Steven? This will bring you pleasure?”
“Yes, Thor, it will. I promise.”
“I would not see you hurt.”
“You won’t. I trust you and Tony; I know you won’t let anything happen to me.” Darting his tongue out, he licked at the tip of Thor’s thumb resting just under his lower lip. “I want this, Thor.”
Thor’s eyes still held a trace of concern, but he nodded and pulled Steve down for a kiss. It wasn’t exactly slow and languid; Steve was too excited and turned on to wait very long. He pulled away to grab the lube off the bed from where Thor and Tony had prepped him earlier and squirted some into his hand. Then he slid back a bit and wrapped his hand around Thor’s cock, using long, tight strokes to bring Thor to full hardness and spreading the lube around evenly. Then holding Thor’s dick in place, he raised himself up over it until his hole was just touching the tip, let go, and slid down until Thor was fully seated inside of him.
Twin groans from each of them filled the room, along with a small moan from Tony who was watching avidly. Steve gave Tony one last nod and began to move, raising himself up and down in a slow steady motion, Thor’s hands warm and reassuring on his hips.
He felt it when the collar began to tighten, not obstructing his breathing, not yet, but enough that he was very aware of it, knowing that any more and it could begin to cut off his air. He slammed down a little harder on Thor. “Please, Tony,” he whispered. “Do it. Please.”
He managed a few more strokes and then Steve felt the collar tighten more, this time cutting in just a little bit. Steve gasped, shuddering, reaching forward to grip the headboard to steady himself. “More,” he gasped.
Tony seemed to control the collar in time to Steve’s thrusts. As Steve and Thor got closer to coming, the constriction increased, tightening more and more until Steve was gasping for air in earnest, truly struggling to draw in the next breath. He could feel his orgasm coming, his balls drawing up, he needed a little more, just a little more....
The collar tightened again, and this time Steve tried to draw in a breath to no effect. He couldn’t breathe at all, his body begging for oxygen even as it was denied to him. Time seemed to slow down, the seconds stretching out as his need to breathe and his need to come battled inside him. His orgasm slammed into him as his vision went unfocused and gray around the edges. He came, bucking and shuddering, tightening almost painfully around Thor, feeling Thor’s fingers bite into his hips, the warm rush of come deep inside him.
Steve must have blacked out for a minute, because when he came to, he was on his back, propped up against Thor, the collar off of his neck. Something was patting his cheeks and he blinked his eyes open to see Tony kneeling in front of him. “Steve? Steve, are you okay?”
He was more than okay. He was fantastic, his body loose and pliant and completely sated and relaxed in a way he hadn’t felt in far too long. And this time it was without the frantically racing heartbeat or inability to get his breathing back under control like how it had always happened before. “‘m good,” he mumbled, reaching out to pull Tony close and he snuggled back into Thor.
Thor pressed a kiss to the top of Steve’s sweaty hair. “Truly? You have not been harmed?”
“No, that was great. Perfect. Love you guys.”
“Love you, too, Cap,” Tony said, finally relaxing into Steve’s hold.
“Can we do that again?” Steve asked, fighting sleep long enough to get an answer.
“Yes,” Thor answered. “Though not, I think, too often. And I shall have Tony show me how to work the collar, so that he may enjoy this with you.”
“Sounds good,” Steve said, and taking a deep breath, settled between his lovers to sleep.