Work Text:
"Night Genos," Saitama said through chattering teeth.
There was a snowstorm billowing outside, plunging the temperature of the apartment below 0°C.
"Goodnight, Sensei," Genos returned, watching Saitama tug his bed covers all the way over his bald head.
He could see him continuing to shiver, even beneath the thick blanket. But Genos knew his mentor would refuse to have the heater turned on if he suggested it, so he didn't bother attempting to convince him.
Previously, Genos had offered to pay the difference, if not the entire bill if it would make Saitama able to sleep more comfortably. But Saitama had still stubbornly refused, telling Genos it was about the principle, and assured him he was totally fine.
Suddenly, an idea struck Genos.
"If it is about saving money then.. "
The gears inside Genos' mechanical body began to whir louder - though it was hardly noticeable against the storm raging outside.
"I will manually raise my core temperature high enough that the output should have a similar effect to a small space heater, which would make Sensei more comfortable while still respecting his desire to be frugal."
Schematics played behind Genos' eyes. He monitored the displays carefully to ensure he was still within safe parameters.
Minutes passed, and Genos noticed a gradual decrease in the shivering from Saitama, until finally he stilled completely. Instead he breathed evenly in an out, settling into sleep.
Satisfied with his work around, Genos too let himself fall asleep.
~
Warm.
There was a lovely warmth at Saitama's back, permeating his dreams in the form of a bright yellow sun.
He was on a beach, sun-baking on his stomach. But he wanted to get closer.
Needed to get closer.
So warm...
~
Genos' eyes snapped open, sensors alerting him to movement. He saw Saitama, rolling towards him.
"So warm.." Saitama mumbled, still asleep.
Before Genos could react, Saitama had crossed over onto his futon; blanket cocoon slowly unravelling until it fell away entirely. Saitama then wriggled under Geno's blanket, only stopping once right up against the cyborg.
He tucked his hands snugly between their bodies, while his cheek rubbed up and down on Genos' chest plating.
"Toasty.." Saitama sighed dreamily.
Then he started snoring loudly.
Genos laid rigidly on his side, processing.
This was not an outcome he had foreseen.
But he didn't hate it.
He didn't hate it at all.
Saitama wasn't a touchy person. This was the closest bodily contact the two heroes had ever shared that didn't involve Saitama collecting pieces of Genos off the battle field.
It was nice.
Though it also felt selfish to indulge. Like Genos was taking advantage of Saitama somehow.
"But.."
Genos spared a glance down to his sleeping mentor. He looked truly blissful, drooling a stain into the front of Genos' shirt.
"Sensei's sleep is important. So, although it was not the intended outcome, if laying close to me will facilitate a restful REM cycle for Sensei, then that is what matters most."
Genos allowed his own eyes to close again, determination set in his features.
"And if it upsets Sensei, I will take full responsibility tomorrow."
___
Saitama was the first to wake.
He hadn't moved again in the night, still nestled comfortably against Genos, who continued to radiate a pleasant heat.
"Huh.." He said, blinking slowly up at the cyborg, not having expected him to be there.
After a moment, Saitama looked over his shoulder to his own empty futon, then back again.
"Didn't know I moved that much in my sleep..." He commented curiously.
Genos stirred at his words, his own eyes slowly fluttering open.
"Hey," Saitama said up at him, "You're really warm, Genos."
The events of the night before came flooding back, and Genos once again went rigid, and bowed his head apologetically.
"I'm sorry, Sensei!"
"Woah - volume dude.." Saitama winced, "No need to yell so early!"
"Since you do not like wasting money on heating I raised my own core temperature to take the chill out of the room. But then you migrated over here during the night, and I did not want to disrupt your sleep," Genos explained dutifully.
"Oh.." Saitama replied, still making no move to separate himself from Genos. A fact Genos was very aware of.
"..That's actually pretty clever," he smiled after a moment, clearly impressed at his (self-proclaimed) disciple's regard for money saving.
"Thank you, Sensei!"
Saitama brought one of his hands up to Genos' chest, resting his open palm on the chestplate, and patting it curiously.
Genos redoubled his efforts to remain perfectly still, fighting a foreign desire to reciprocate his mentor's touch in some way.
"You're not creating a fire hazard being this warm though, right?" Saitama asked with concern.
"No Sensei," Genos assured him, "I am closely monitoring my temperature to keep it within a safe range."
Saitama turned his head to the window. Snow was still whirling by outside.
"So you don't mind if I stay here, then?" he asked, giving a pointed glance at the small space between them on the futon.
Genos could feel the steam building in his vents. He couldn't look Saitama in the eye.
"No Sensei," he confirmed quietly, trying to keep his voice even, "I do not mind."
There was a small pause. Genos steeled his nerves.
"In fact," he continued, even more quietly than before, "It is quite pleasant for me also."
There was a pause where Genos' admission hung guiltily in the air.
While likely only seconds, it felt like minutes passed before Saitama responded.
"Oh."
Genos eyes flickered to his face to gauge his reaction. To most, Saitama's would have looked as blank-faced as always, but Genos had come to recognize this expression as one of processing.
"Cool," Saitama concluded nonchalantly, and without further warning, lowered his head back onto Genos; using him as a pillow.
"Or should I say "hot"? Bah-dum-tss," he chuckled into Genos' shirt.
Steam burst forth from Genos' vents like a boiling kettle, right into Saitama's face.
"Woah!"
"Sorry Sensei!" Genos exclaimed, flustered and trying to create distance between them.
But Saitama's hand was on his hip before he could get far, reflexively -and seemingly unaware he even did it himself- steadying Genos.
"Ooh, that's actually pretty nice," Saitama commented, eyes following the lingering trails of steam that wafted from the cyborg's arms and shoulders, "Good thinking, Genos."
He settled back down again with a contented sigh.
"Thank you, Sensei.." Genos replied softly, left with few options but to roll with the compliment.
Perhaps at a later date, when he better understood his own confusing feelings, he could admit to Saitama that the burst of steam was entirely involuntary.