Eren had quickly learned how to tell when it was going to be one of those nights. Armin would speak less, even when prompted. He would eat dinner more slowly than usual. He would forego reading a book before tucking himself in and leaning into his pillow right when the sky began to darken.

The rest of the trainees would trickle into their beds in the dim candlelight coming from each corner of the room. Once nearly everyone had stripped off their muddy boots, peeled off shirts damp with sweat from their exercises that day, and shoved themselves deep into the scratchy wool bedding, the candles would be blown out and Eren would start waiting. Sometimes it took longer than others. Most nights it took only a few minutes. Tonight Eren stared at the bunk adjacent to his, at the strands of blond hair and the glow of a pale cheek reflecting the moonlight coming in from a nearby window. Eren mentally counted the seconds. It would take only a few minutes before the movements started.

Armin was subtle enough about it. All of the boys had learned to be. After sharing living quarters with a dozen-odd soldiers for a month, you learned your options were pretty slim: wait until everyone was asleep (there would always be one or two still awake, but you learned to ignore them, especially if their movements began to mirror yours), take care of it as quickly and painlessly as possible in the cold showers (near impossible, but everyone had tried it at least once), or find someone else to do it for you (an option for only the bravest).

In this situation, of all things, Eren was not brave.

Eren forced his breaths to even out as his eyes, now adjusted to the dark, fell upon Armin's form, lying on his side, facing away from him. He wouldn't start until he was certain everyone in his immediate area was asleep. Though he knew Armin could not see him, Eren still closed his eyes, a habit formed from feigning sleep one too many times. He had already tucked his hand quietly into the band of his boxers, allowing his palm to rest against his hip, letting his fingertips graze against the coarse hair there. If Armin heard Eren moving, he would stop, so Eren was as quiet as possible, employing every ounce of subtlety he was capable of. From across the room, he heard the light snore of one of his fellow trainees.

Movement.

Eren could hear the whisper of sheets shifting against one another as Armin rearranged himself. He allowed his eyes to blink themselves open gradually. Armin's hips were still facing away from Eren, but his shoulder had fallen down onto the mattress, his back twisting, and the shadow of Armin's profile showing in the dim light. Despite the dull lighting, however, there was no mistaking Armin's small gentle movements. His hip moved in tandem against the movements of his arm. The noise of the sheets was especially obvious tonight. Armin wouldn't usually be this obvious.

Though he was almost certain Armin had no knowledge of it, every time Armin had touched himself for the last several weeks, Eren had watched and touched himself too. He wasn't sure how precisely this strange routine had come about, because when he had first accidentally caught Armin in the act, he'd been more shell-shocked than anything. Armin, in Eren's mind, had been this non-sexual entity. He was small, fragile, someone to be looked after and protected. So, when he recognized Armin's panting breath and steady, gentle movements underneath the covers for what they were, his initial reaction was to simply stare, mesmerized. He watched Armin's thin wiry frame lurch, his pale back arching, his hand coming to his mouth, and his teeth biting down on the knuckle of his thumb. Eren was fascinated by it. He watched as Armin brought himself to orgasm and after that he just kept watching. He watched Armin clean himself with a small cloth from under his pillow, watched him turn onto his side, watched him drift to sleep, and watched his chest expand with each deep breath until Eren himself finally lost consciousness. The second night he caught Armin, Eren turned over and shut his eyes tight, as if clenching his eyes shut harder would block the rapid swishing sounds of the sheets moving against Armin's hand. Despite his efforts, however, it took Eren more energy than he cared to admit to ignore the stirring in his boxers that arose when Armin finally came with a quiet whimper.

From that point on, whenever he would catch Armin, Eren would get hard, and either keep watching, grinding against his mattress hard enough to make himself come in his pants, or tell himself that what he was doing was an invasion of privacy and he would do extra chores the next day as a sort of penitence. Then one night, when his fear of death had finally surpassed his fear of his best friend catching him watching, Eren let his hand quietly sneak into his starched white boxers and brought himself to orgasm just before Armin. The next day, the barracks were absolutely spotless.

With a quiet, airy huff of breath, Armin brought Eren back to the present. Eren was already hard. He let his fingertips move up the length of his dick slowly, holding back a shudder. He breathed as quietly as he could, so he could hear Armin's breathing better. Armin's jaw was twitching with each breath, though no substantial noise came out. Just quiet, quickened inhales and exhales. Eren let himself get lost in them, letting his hand fully grip his cock, moving up and down in time with Armin's panting breath. Every so often, his breath would hitch and Eren would have to bite his lip to avoid letting out a moan. These nights, Armin was a different person. He let the layers he usually protected himself with chip and break away. This was Armin Arlert in his purest form: lying in the least comfortable mattress in the world, his body twisted, and his breath catching in his throat at the feeling of his own hand wrapped around his dick.

Armin's hip finally fell down onto the mattress, letting him lie fully on his back. His outline was much more obvious now. One of his hands was making its way from navel to nipple and back again in a slow, steady rhythm, like he was putting on a show. Now his other hand's movements under the sheet were so apparent now, it was obscene. It was working at a much faster pace than the other, faster than Armin usually would. Eren adjusted the speed of his own hand to try and match him.

Armin's light breaths were getting caught in his throat more and more often, his tongue periodically darting out to run across his lips. He was getting close. Eren could have come minutes ago, but every time he approached the cusp, he eased off and let himself cool down. It always felt best when he came with Armin.

Armin's movements began to stutter. He wouldn't last much longer now. Eren let himself approach the edge as he bit hard into his lower lip.

Armin suddenly twisted onto his side, facing Eren's bed.

Armin's eyes, reflecting the faint moonlight, were staring into Eren's. Armin's breath caught in his throat, and for a second, everything was still. Then, still staring, shocked, into Armin's bright blue eyes, Eren was coming. The thrill of his orgasm frenzied through his stomach and slammed his eyes shut, the image of Armin's face, his eyes wide and mouth parted slightly, still burning in his memory. His hips jutted forward of their own accord and he felt his release spill over his hand. Still breathing heavily, not bothering to choke his breaths down anymore, Eren opened the eyes he had shut in his ecstasy to look over at Armin.

He managed to catch Armin just as his head was thrown back. Eren heard the faintest moan over his own pounding heart and jagged breath. He watched Armin's hips stutter under the sheets, watched the hand that had been ghosting over his stomach grip the edge of the scratchy wool tightly, for what seemed like forever. Then finally, Armin was done, and the room was filled with the sounds of their breaths, heavy and out of sync.

Eren stared at Armin, who had settled back down to lying on his back, staring at the ceiling. He waited for Armin to say something, to break the silence. Maybe tonight Eren would have to be the brave one.

"Sorry," Eren whispered towards Armin's figure. He watched Armin's chest rise and fall with each lungful of air. After a few moments, Armin's head moved up and down in a slow nod.

"Are we okay?" Eren asked, staring at Armin's profile, at the soft slope of his nose and his half-opened lips.

Armin's head fell to the side and his eyes met with Eren's for the second time. His eyes were so big. Eren could never get over the fact that, even in this dim moonlight, his eyes still looked just as beautiful as they would be on the brightest of days. The barest hint of a smile played across Armin's lips.

"We're fine."

Thanks for reading. This story is also on AO3