a/n: ah, I love a good pair of bros. This probably doesn't follow the prompt, and I've used this trope a million times, but eh, idc, I'm dumping it here anyway. Thank you for reading.
Rin had been awake for almost an hour when he heard muffled gasping and whimpering on the other side of the dorm.
He blinked, confused and surprised. With his brows raised, Rin sat up, gently maneuvering Kuro off his lap and whispering quietly, "Yukio?"
He was greeted with silence. But as much as Yukio tried to hide it—was he holding his breath? Did he really think that would work?—Rin was not fooled. Even in the dark, he could see the tremors that claimed his brother's body.
"Yukio. You're obviously not asleep." Rin was frowning as he slid his legs over the side of his bed, tail lazily untangling itself from his blanket. "What's wrong?"
Silence.
"Damn it, Four Eyes, I—"
"I'm fine."
Rin's eyes narrowed at the stoic response. His ears were sensitive enough to hear the slight quiver in Yukio's voice. Wordlessly, he stood. Then he was crouching beside his twin's bed, a hand coming down to rest on Yukio's shoulder.
Yukio stayed facing away from him and did not react to the gesture. Rin asked, "Did you have a nightmare?"
No response. Rin sighed. "C'mere."
"Nii-san, I don't—"
"Shut up. I can see you shaking."
Yukio fell quiet again, and Rin's response was almost instinctive at this point: crawl into the bed and pull him close. Despite Yukio being a little taller than him, he seemed small in this moment, body folded up against Rin's chest, head tucked under his chin.
Nights like these happened too often, ever since they were tiny children, but neither of them spoke about them the next day. Neither of them needed to. Because Yukio was all hard looks and cold professionalism, a prodigy exorcist with no room for emotion. Because Rin oozed overconfidence that no one knew was false, an image of unwavering strength and foolish optimism.
"Sorry I woke you," Yukio murmured tiredly after a time.
Rin hummed under his breath and stared at the wall as his brother's body relaxed slightly. "No big deal. Try to go back to sleep."
Yukio nodded numbly and silently. Rin let his eyes drift shut and, like always, purposely omitted the fact that he'd suffered from the same thing that had caused Yukio to awake so violently.
The small conversation had, after all, calmed them both down enough to beckon them back into slumber.