"Armin," Eren said, a serious expression on his face. "Have you ever thought about what if we could design our own uniforms and I could have a pink dress with a white petticoat and red heels and you could dress in purple and black and have the power to control the flow of time."
Armin didn't even look up from his book. "I honestly haven't."
Eren nodded thoughtfully. "That's probably alright. Your legs look amazing in our normal uniforms anyway."
Armin was in his lap, which provided the perfect opportunity for Eren's hands to sneak around his hipbones and rub beneath the cross of straps on his hips. Armin tilted his head to the side, considering.
"That's not my legs you have your hands on, Eren," he said mildly. He gave a slow, subtle roll of his hips.
"Nah, it's your dick." Eren rested his chin on Armin's shoulder as his hands made quick work of the button and zipper of Armin's trousers, and dipped inside to skim his knuckles against his cock. He nuzzled the skin of Armin's throat with his nose. "Wish I could get you up against the wall right now in nothing but your boots and harness."
Armin gave a long, tremulous oh. "What would you do to me then?" he asked, his hips rocking into Eren's fist.
Eren's eyebrows raised. "I'd fuck you?"
He'd thought his intentions were obvious. Armin gave a low groan.
"Of course you would." Armin reached back to grab a fistful of Eren's hair, to steer his head and their lips together. "Would you…ah, would you strip down, too? Or would you just unzip and fuck me senseless?"
Eren panted against Armin's mouth, his cock rubbing against Armin's ass as he ground against him. He'd unzip and shove his pants down just enough, he wouldn't have the patience for anything else with Armin like that in front of him. Then he'd grab the straps crossing Armin's ass, use them for leverage to hold Armin in place as he pounded into him—
They came in their pants, messily. Eren leaned back against his chair to catch his breath, dragging Armin with him with a hand against his chest. Armin gave a tiny grunt of displeasure at being forced to cuddle with someone with a soaked crotch, but seemed to settle into it easily enough. Eren's fingers idly toyed with Armin's chest buckle. You could get come stains out of pants easy enough, but did that go for leather too?
Well, they'd find out soon enough, Eren reasoned.