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Thor asks, “Why does Tony Stark call you ‘Gramps’?” late one afternoon in their bed, elbows planted on either side of Steve’s hips.
Steve has come more times in the last four hours than he thinks he’s come in all the previous years of his life combined. Thor had been tracing a lazy, meandering path over the flat of Steve’s stomach with his mouth while waiting for Steve’s superhuman, but far from godlike, refractory period to kick over. Steve is loose and languid from the crown of his head to the soles of his feet, and it takes him a moment to even understand the question.
“It’s, ah, a joke,” Steve says, folding his arms behind his head. “I’m technically -- ninety-four, I think. Ninety-three? I’m old enough to be a grandfather, and Tony thinks it’s funny.”
“A grandfather,” Thor repeats, mouth turning up at the corners in a small, wry smile. “But that is a mortal notion, I suppose.”
The rough rasp of Thor’s beard against his skin has Steve’s cock beginning to stir. They’re alone in the Tower, for the first time in months, and Steve feels a little like a teenager at play while his parents have gone away for the weekend. Not that Steve ever did anything like this when he was a teenager; the closest he got was with Bucky, sticking their hands down each other’s pants when Steve’s mom pulled a double shift at the hospital.
“Ninety-four is fairly old,” Steve says, shifting his hips.
Thor laughs. He presses his face to Steve’s skin and Steve can feel the hot huff of his breath and see his shoulders hitch in amusement. “What!” Steve reaches down and tangles his fingers in Thor’s hair, tugging until he raises his head. “It is,” Steve insists.
“For a mortal,” Thor says, shaking his head like a parent amused at the antics of their child. “To me you are but a child, Steven. You are an infant.”
Steve arches an eyebrow. “An infant, really?”
Thor straightens as best he can positioned on his stomach with his shoulders held up by bent elbows. He looks at Steve, eyes bright and still amused. But there’s something deeper than that beneath it, sharp and bright and alien. It’s easy to forget, once you get used to his anachronism, that Thor isn’t the strapping man he appears to be. He is no more simple human than the Chitarui, and no more a young man than Steve himself.
“An infant,” he repeats slowly, pushing up onto his hands and knees to crawl up the bed until he’s aligned with Steve, looking down at him with impossibly bright blue eyes. “Steven, you have lived but a blink, little one. Even with your frozen sleep. The grandfathers of the universe were there when it began, when Yggdrasil came to be.”
Thor’s thigh pushes between Steve’s legs and Steve shudders a little. The heat that comes off Thor is -- it’s electric, for lack of a more apt and less obvious description. Steve pulls his hands from beneath his head and pushes his fingers along the line of Thor’s jaw to cup the solid, graceful curve of his skull. Steve is superhuman, but Thor is indestructible.
“What about you?” Steve asks, softly.
Thor smiles. “I have seen eons, Steven. What is so far in your past it is all but forgotten, but for remnants and stories, I have seen.” He bends down, murmuring the words to Steve’s forehead and cheeks and lips. “Five hundred of your lifetimes would not bring you close to how old I am, my youngest grandfather.”
Steve laughs a little, low and breathless. Thor’s thigh is solid, hot friction against his cock and Steve is too damn old to be rutting like a teenager, but Thor does this to him. Has done this to him from the moment they first met. It’s nonsensical, the way Steve goes from feeling like a dusty relic brought up from the basement, a curiosity no more useful than just about everything from his own time, to feeling like a teenager running recklessly through the world like he couldn’t when he was actually that young.
“And that makes me an infant?” Steve asks, the ends of the words trailing off into a soft ah.
Thor nips at his bottom lip, pressing his thigh upward until Steve grunts out a noise and lifts his head, pressing his forehead to Thor’s shoulder. “A child,” Thor amends, voice suddenly gone rough around the edges. “A sweet-faced, unblooded youth with a wooden sword in his hand. Too old, perhaps, to chase dragons through the hall, but not yet old enough for steel. Were you Asgardian--”
“If I were Asgardian, I would have followed you around like a puppy,” Steve says, pinioning his hips against Thor’s solid, implacable weight.
Thor laughs, and the sound is rich, and amused, and a little hungry. “Were you Asgardian, I would have taken you under my protection,” he says, pushing his arms beneath Steve’s shoulders so his weight suddenly has nothing else to rest against but Steve’s himself. He rolls his hips, and Steve can feel his own equally interested cock caught between them. “I would have taught you, little one, and put your first steel in your hand. I would have taken you to glorious battle and seen you spill first blood, and known you were of a man because of me.”
“I would have been grateful,” Steve gasps. “I would have -- hero-worshipped you.”
“You would have worshipped me,” Thor corrects. “Little one, my child I forged into a man.”
Steve’s toes curl inward at the low roil of heat in his belly. “You do that anyway,” he gasps.
“Yes,” Thor agrees, and there is a breathlessness to his words. “You are my little one, my mortal and I make you more, as you make me more. You take the ages from my shoulders, Steven. Were you Asgardian,” he repeats, and there is possibly something wistful there. “I would have taken no other child than you, and you would have been my greatest feat.”
“Would we have done this?” Steve asks, digging his fingers into Thor’s skin, knowing it won’t bruise and almost wishing it would.
Thor’s breath comes in strained, low huffs. “Not before you were blooded, young one. You would have been impatient,” he says and Steve almost laughs, but it comes out as a choked gasp of need. “But I would have made you wait until you were a man.”
“I thought -- I thought,” Steve grunts, feeling the edge come up on him. “I thought I was an infant.”
“Ah, Steven, my young one, you are--” Thor says, “You are mine.”
Steve comes with a sound very much closer to a sob than he will ever admit to, thrusting against Thor’s hips like a teenager gone frantic with the new crash and crush of need. Thor’s arms are so tight around his middle he can barely breathe, but that’s good. Steve likes that, to feel small and insignificant and young held to Thor. Steve presses his face to the curve of Thor’s neck and his senses suffuse with the scent of him, leather and earth and steel.
When Steve has jerked and shuddered through the aftershocks, Thor eases off him but stays close. He throws his arm over Steve’s middle and tosses a leg over Steve’s thigh, crooning softly to him and rutting against Steve’s hip. He comes with a noise that Steve feels more than he hears and suddenly becomes a warm, satiated weight against Steve’s side.
“I suppose we owe Tony a thank you for that,” Steve says with a chuckle, when he’s found his voice.
Thor snorts against his shoulder. “Tony Stark’s soul is a child’s soul. He could live to Ragnarok and never be aught else.”
Steve laughs, throwing the back of his hand over his eyes, and after a moment Thor joins him.