Contrary to apparent popular public opinion, Steve Rogers, Captain America, wasn't a prude. Tony always knew that, long before he got to experience first-hand just how not prudish Steve was. But even Tony had to admit he was caught off guard the first time Steve walked up behind him, leaned his chin innocently on Tony's shoulder, and slyly, deliberately, groped his ass, all the while carrying on an casual and uninterrupted conversation with Hank across the kitchen counter.
Hank didn't seem to notice Tony's gasp, or the way his breathing started to pick up when he realized Steve had no intention of stopping. The conversation ran its natural course, though Tony had lost the thread by the time Hank left the room, and Steve tilted his head, planting a kiss on Tony's jaw.
Steve was skilled - skilled and thorough. Tony, at that point, had had three weeks and six days of experience to attest to that fact; but three weeks and six days still weren't enough to prepare him for being shoved face first to the mattress while Steve's unnaturally talented tongue teased circles around his opening, sliding up the cleft of his ass, then back down to tease again.
"Oh, oh God," he gasped at a near-embarrassing pitch, "Steve, oh God."
One spit-slicked finger, followed quickly by a second, pushed inside him, and Steve kissed the small of his back, murmuring, "I love your ass." Lips ghosted up his spine, fingers driving in with a force Tony couldn't recall Steve ever using before. He rocked back, encouraging silently, not wanting to interrupt this unexpected turn of events with incoherent pleading; Steve usually left Tony in charge of the talking in bed. "I love... how it feels, sometimes I have to stop myself from just..." Steve's free hand grasped one cheek in demonstration.
Tony took a gasping breath, blinking hard to clear his head. "I wouldn't complain if you stopped fighting those urges, you know."
Steve growled, settling flush to Tony's back, the dripping proof of his claims pressing into Tony's thigh. "Love that sound you make, and how you push back, I love how much you love it."
Tony whimpered, responding with the rocking of his hips, without a response, just basking in the praise.
A third finger joined the first two, and Steve was practically panting in his ear, "I love having my fingers in you. You're so tight, it's like you're teasing me and you don't even know it."
He felt a stretch and burn as Steve twisted his fingers, reeling at the words, at the very idea that Steve wanted him that much.
The fingers disappeared and Steve's erection pressed against his opening, barely pushing in. The "please," slipped from his lips before he could stop himself, and his reward was a low groan.
"God, Tony," Steve's voice sounded strained, and he moved forward a fraction, filling Tony a little more, "I love it when you beg."
It was like breaking a dam. "Please, please, Steve," Tony shook with the effort not to thrust back and just impale himself, "Fuck me, please, I need it, Steve, I need you."
"Fuck," Steve rasped. One hand threaded through Tony's hair, holding his head down, while the other gripped his ass hard, spreading. "You sound so good when you say that," he said, and pushed in.
It was hard and fast, rougher than he'd ever been before. He held Tony down, pinned him to the bed as he thrust, as Tony sobbed and clung uselessly to the remnants of higher thought. He could barely keep up with Steve's pace, but he arched his back, held his ass up to give the perfect angle, babbling incoherence into the pillows, too desperate for shame.
Tony came first, spilling over Steve's fingers as soon as he was touched, groaning, relishing in the deep, satisfied growl that rumbled through Steve's chest.
He could feel himself tighten, could feel the thrusts get messier, more erratic, but it was still minutes before Steve gave in. Tony took every shock of overwhelming pleasure, rocking back with no less force than before, thrilled at letting Steve use him. He was still moaning when Steve came; he probably would have still been begging if he could have formed the words.
It was a long time before either of them moved again, and Tony had to force himself not to whimper at the loss when Steve pulled out, collapsing to the side. It seemed like a good time to comment about setting precedents and raising expectations, but then Steve drew Tony to his chest, and witty banter suddenly took a back seat to nuzzling Steve's neck, curling in close, and falling asleep.