For the purposes of this fic, I'm assuming Prom had laser eye surgery at some point, negating the need for endless faffing with contact lenses. XD
Faced with the sudden, eye-widening expanse of Noct's pale back, warmed slightly by the faint yellow glow of the single light source, it occurred to Prompto how little skin-to-skin contact they had ever had, in spite of his own tactile nature. Even when they high-fived, there was usually at least one pair of leather gloves in the way.
"You have really good skin," Prompto blurted out.
Noctis burst out with a brief, musical laugh. "You're so weird."
"Hey, you gotta be nice to me. Or I'll work you so hard you won't be able to walk straight tomorrow."
As the innuendo of his words rapidly became apparent, the atmosphere tensed and tingled as both men cleared their throats awkwardly, saying nothing.
"…That…kinda came out wrong," the blond admitted after an agonising few moments, laughing uncomfortably.
"…A bit, yeah. So, I guess…you can start now?" Noct scratched subtly at his own cheekbone, hoping Prompto wouldn't notice (or at least, draw attention to) the hot blush he felt beginning to stoke under his skin.
"Right," Prompto nodded, scrunching his fingers against his palms to flex them, and then sweeping the long damp hair at the back of Noctis' neck to one side.
"Don't wanna snag it," he said by way of explanation.
"Hey, you're the professional here," Noct teased, sitting quite calmly, eyes ahead and face still burning, seemingly impossible to quench at this juncture.
"Right, starting now. If it feels…weird, or bad, or…whatever, just holler and I'll stop."
"'Kay."
Prompto rested his slightly-calloused hands on top of Noct's broad shoulders, and just let their natural weight form the pressure upon the muscles there. With a few experimental squeezes of his palms, and gentle prods of his thumbs, he tested the muscles.
"Gee, you are really tight," he observed, wincing as he imagined the ache within them. "How long's it been hurting?"
"…A while. It was worse today after the hunts." Noct mumbled vaguely. "Didn't want to waste a potion on it."
"…Right, let me just…"
The Prince heard and felt him shift on the bed, the mattress dipping again, and one of Prom's joints clicking loudly. He was just imagining his friend's face, probably contorted in concentration and with his tongue sticking out, when two strong thumbs smoothed up and across the gritty knots in his trapezius muscles.
"Ugh…shit!" Noct exclaimed, his head dropping back as he hissed in air through clenched teeth. Before the startled blond could start apologising, Noctis laughed throatily, and brought his head forward again with a deep sigh. "…Feels amazing."
"Oh…Phew! Thought I'd busted something," Prompto giggled in relief, replacing his thumbs and repeating the move, kneading the solid muscles between his digits, becoming quite invested and interested in the massage, already feeling quite proud of himself.
Noct swallowed loudly, and groaned to himself, his head hanging low and Prompto pushed a little deeper, and extended the area of his labours, rolling over the bumps of the Prince's shoulders, and back to his neck, gently digging into pale flesh to work out the deep-seated stiffness.
"…Prom…ugh…mmh," Noct was murmuring quietly, eyes blissfully closed and lips parted, melting under his administrations. Prompto tried very hard not to pay attention to the soft, gut-wrenching moans of his friend, who clearly hadn't been kidding when he said he wasn't used to being touched. For ten minutes, he pushed his fingers across ribs, around slim shoulderblades, always coming back to thumb and probe at his neck muscles. He had initially prayed that Noct would shut up and quit making sounds like he was jerking off, but that had been futile, the Prince had continued to swoon and sigh under his ministrations.
"Nh…harder," Noctis finally seethed, practically swaying on the bed. Prom could almost believe he was in some kind of massage-induced trance, especially considering how open and unabashed he'd been the whole time.
Steeling himself, and dredging up a heroic amount of fortitude, Prompto shuffled back, holding his palms flat against Noct's back in case his friend physically tried to force himself backwards into further massage.
"Actually, I think I'm done," Prompto informed the back of his friend's drooping head as brightly and unassumingly as he could.
"…Hm? No, carry on, that was great. 'mazing," Noct repeated, finally turning his head and fixing sleepy indigo eyes upon the photographer, looking almost drunk.
"That's all I know!" Prompto shrugged, backing off of the bed with only a slight wobble and guiding the boneless Prince to lay on the mattress, facing away from him. He pulled the downy-soft robe back up, covering Noct with it like a particularly plush bedcover.
"Just, stay there and breathe and relax, okay? And sleep, that's what you need," Prompto babbled hastily. "Close your eyes and just totally chill."
Prompto's instructions seemed to be getting further away, until Noctis heard him turn, stumble, catch himself, and then almost sprint into the en-suite, closing the door and locking it with some force.
Blissed-out, pain-free, and happier than he had felt in a long time, the Prince just mumbled faintly to himself before curling up in his bathrobe, closing his tired eyes, and getting ready to succumb to sleep. Before his hazy thoughts melted into dreams, he allowed himself a few exploratory, lazy pumps of the erection he'd sustained (and luckily been able to keep hidden) during the massage. Very soon though, lethargy overcame lust, he slipped his hand out of his underwear, and fell deeply asleep.
Prompto had convinced himself whilst in the shower stall, masturbating frantically, that firstly, his trip to the bathroom wasn't suspicious, because he hadn't showered since yesterday. And secondly, Noct was bound to be spark-out when he returned, so he wouldn't be questioned anyway.
It had taken him no time at all, in his urgency, to slam and lock the door, rip back the shower curtain, turn on the water and strip. By the time he finally got his hands on himself, he was primed to explode, and despite not using any of his usual tricks to get himself off quickly, he found himself gasping and trembling on the precipice of orgasm within twenty seconds. One hand on the cool tiling of the wall, supporting his quivering weight, he sank his teeth into his bottom lip, sobbing.
Wasting no time, he viciously rubbed himself into a dizzying climax, and in the mindless euphoria of it, he was only distantly thankful that the deluge of warm water was drowning out his rough, strangled groans.
Five minutes later, bleary-eyed, empty-headed and weak-kneed, Prompto sneaked back out into the bedroom in his own fluffy robe, having cleaned up both himself and the shower. Still trembling a little, and his lungs feeling just a little wheezy, he flicked off the bedside lamp between their beds with a gratified sigh, pitching the room into a sudden cool darkness. Silver-blue stars danced briefly in front of his eyes.
Sitting heavily on his own bed, which was chilly to the touch and pristinely clean, he eased off his robe and snuggled under the sheets, his own tiredness burning his eyes and mellowing his thoughts.
He lay on his back, one hand on his stomach, which was still twitching faintly from the effort of his orgasm, and soon drifted off, lulled by the purring little noises that emanated from his sleeping roommate.