It was echoing in his head over and over, his mind resembled a broken record playing on a gramophone whose needle kept on jumping over some deep scratch. In Eren's case, the repetitive sound was 'holy shit' and why was it so, someone might ask... but the young soldier was far too preoccupied with trying to contain the twitching of his limbs to answer.
It was 5:30 am at the moment, most of the people in the castle were still asleep or out on patrol, or scheming/about to make things explode, but Eren couldn't sleep any longer and he couldn't stand to just lie in bed for another half hour until it was time to get up, for this reason he'd decided to grab a change of clothes and head up to the communal showers. It'd been a couple of days since his last one; captain Rivaille had been kind enough to point out he was starting to smell like Hange, the night before, which meant it really was time to wash more thoroughly then the usual half-assed ablutions at neck, face, arms and hands.
The last thing Eren wanted was to disgust the captain away.
Back to Eren's short-circuited brain — well, he hadn't expected company in the showers, but if he had the capability to actually think things through he would have imagined the current situation as possible, and the situation entailed: captain Rivaille was there, stepping out of his uniform's white pants, which he threw in a laundry basket along with the already-discarded white shirt and cravat. Eren was sure he'd stopped breathing by the next second, watching the other's thumbs hook onto the waistband of the tight, standard military-issued boxers, about to pull them down.
Eren's eyes caught the involuntary spasm of a gear-scarred thigh. "A muscled, thick, creamy-white thigh..." Finally his brain seemed to unfreeze, but with it, Eren ended up remembering another reason for his decision to leave his basement room: he'd woken up with an annoying morning erection and the sight before him now wasn't helping in making him forget about it. Rather, the moment in which the captain apparently felt the hungry stare of a hormonal teenager ogling him, gave Eren an even harder time because the man turned around in slow mo - or that's how Eren perceived it -, clothed crotch in sight.
A strangled noise escaped him, eyes glued to the boxer's waistband that hardly covered what was underneath but let the barely-noticeable patch of black hairs visible. Eren felt the twitching in his limbs worsen, his hands curled at his sides, and when he lifted his focus a little bit north, the sharp V between Rivaille's hipbones almost had the soldier's brain shut down altogether. «... Shit...»
«The fuck are you doing here, Eren?» The captain's voice was thicker then usual, and if Eren had enough brain cells functioning he would have guessed it was due to tiredness and lack of sleep. Of all the things Eren could have imagined the captain asking him right then, he found it strange it was nothing to do with his inappropriate gawking — in all honesty, he thought Rivaille to be somewhat particular about people seeing him in any state of undress... yet there he was, in the shower room, standing before Eren in just his underwear and looking perfectly comfortable, if maybe slightly irritated that his alone-time was interrupted.
«I asked you a question.» Said the captain, a hand going to rest on a hip.
"... And strong fingers able to use a reverse grip, corded forearms I'd give anything to sink my nails in—"
«Uuh...» Said Eren, bringing his eyes to Rivaille's; well, that had been his intention, but on the way there, they'd gotten trapped at the sight of a glorious torso equipped with an eight-pack, gear-straps bruises and pecs Eren would give away his measly military-wage to run his tongue ov— "Fuck." he thought, a hand flying up to his face to make sure he wasn't drooling. He wasn't, thankfully. «I, uh, couldn't sleep, I thought I'd come up here to wank— wash! Fuck, I meant... to wash, to- to take a shower.»
"Wow, please let a titan stomp on me right now." Eren pleaded in his head, he wasn't even embarrassed; no, he was far too horrified at his slip-up to flush.
An amused huff passed through the captain's lips as he reached a hand to his shower knob, turning it to let the water warm up a little. Keeping his eyes on Eren, Rivaille took off his boxers and stepped back, under the spray. «Do what you want.»
It sounded far too much like a challenge and he knew it would have been wiser to do a one-eighty, high-tail it out of there and maybe take care of his boner elsewhere, if at all, but by that point Eren had been enslaved by his hormonal side. He walked closer to the captain as the other reached for the soap bar, he followed the hands movement while Rivaille lathered them up, he kept his gaze glued to path they took along the toned upper body — the captain was taking his time, that much was clear... something that was unusual, as far as Eren knew from the others in the squad, because the short man was known to take the fastest showers in the whole military organization.
"This is torture...!" Thought Eren, and it was almost pathetic how hard he was from just watching the man's fingers press into the muscles, going lower. The paleness of Rivaille's skin gave way a bit under the hot water but the contrast with Eren's own skin was still stark and it was mesmerizing— "Wait, when did I...?" He regained some of his awareness only to realize he'd stepped in the shower with the captain and that his fingers were millimeters from Rivaille's chest.
He was under the same spray as captain Rivaille. He was invading his personal space. He was still dressed - clothes soaked through - while captain Rivaille was naked and he was so close he could feel the heat come off of the other.
And Rivaille was naked. In front of Eren, who sported a rock hard erection that begged to be relieved of its confines. "Fuck."
Eren had no idea what to do... no, not really: he knew very well what he wanted to do, he just didn't understand why the captain hadn't punched him yet, for coming on to him and for overstepping his boundaries... would Rivaille stop him if he tried to do what he wanted?
Somewhere in what was left of his desire-filled brain, Eren noticed the captain seemed to be enjoying watching the conflict he was sure could be seen in his eyes.
(Rivaille enjoyed the attention - he's felt the soldier's gaze on him since day one, each day he saw it change from weariness to hero-worshiping to curiosity, to attraction - but he never thought much of it: it wasn't anything new and he'd been sure Eren would change his mind quickly or trying to keep his infatuation a secret. Rivaille had actually been pleased to see the other's reactions but he wouldn't think of making the first move, ever.)
«If you want to stay here at least strip.» He said, a faint smirk playing on his lips, refusing to inch forward and make contact with Eren's fingers.
While he came to a decision, Rivaille washed his hair, massaging his scalp for a few seconds before closing his eyes and tilting his head back to let the water rinse the foam off. Sighing through his nose a little at the sight of the captain's exposed neck, Eren took off his clothes letting them fall to the shower floor with two wet 'plop's. Now naked as well - not to mention so hard a slight graze would undo him -. he felt self-conscious under Rivaille's sharp eyes, yet it was exhilarating to see the approval in them.
«Captain...» Said Eren, voice strained, «Can I... touch you?» his hand hovering between them visibly shaking with the effort it was taking to not move. The water falling over them became a forgotten background noise as all Eren's focus was stolen by the droplets running down the ridges of chiseled abs, and lower, lower— "Fuck he's hard too..." All the air in his lungs promptly disappeared, heat now definitely turning his cheeks scarlet.
«I already told you it's up to you, idiot.» The captain told him.
It was as much of a 'yes' he was going to get. Taking a breath, Eren finally let his hand rest on Rivaille's chest, over his heart, which he could feel beating steadily and faster then he would have thought. He moved his fingers to run slowly along the horizontal mark left by the gear - the skin was rougher there - and then down man's breastbone; gaining confidence, Eren also brought up the other hand to trace the captain's wide shoulders and neck, his blunt nails digging into the sinewy muscle of Rivaille's upper- and forearms. There were a lot less scars than he'd expected - only a couple.
The captain hummed in appreciation at the touch. Eren gulped down his nervousness and ventured lower, his hands brushing over the other's sides - subconsciously counting the ribs as he felt the bumps under his palms - and abdomen. Eren still couldn't believe he was doing any of that... no more than a few hours back he never would have thought he'd find himself in this position, yet now—
—Now he found himself squeezing his eyes shut while he tried to refrain from coming the second he felt Rivaille's hand closing around his erection. He buried his face in the crook of the other's neck and clutched at his back.
«Keep going.» Told him Rivaille, voice barely above a whisper.
Eren did as told and let his hands roam over the back under his fingers, the muscles hidden beneath shifting as the captain's arm and fist worked to send pleasure jolting through his body. Once Eren reached Rivaille's ass, he grabbed a handful, fascinated by the firmness, and in response the other ground his crotch into Eren's causing both to groan.
«Captain... nh! I'm c-close—»
Eren's hands slid down a bit more, scratching at Rivaille's thighs over the gear marks. «You've been good, Eren.» The captain said, his voice hot over his ear, and it was literally everything he'd seemed to be waiting — with the next rough caress on his length, Eren choked on a moan, coming over Rivaille's fingers and both their lower stomachs.
A minute later, the younger of the two had regained his senses, «Should I...» he asked, flushing a light pink while looking at the other's erection right before him. He wasn't sure he'd do a great job but it was sort of the least he could do, or so Eren thought, but Rivaille shook his head with a barely-there smile.
«It wasn't about me.» He said, «Now hurry the fuck up and shower, or get the hell out of here.» the rude remark wasn't really enough to hide how seriously he meant the first part.
«Alright, captain. Maybe next time, then?»
«Ch', don't get too cocky now, Eren. You might get more than you wished for.»
«I sure hope so, captain Rivaille.» Eren said, smirking.
Being thrown out the stall was worth the amused huff and the smile he got out of the shorter man. He couldn't wait for the next time.