River found her brother in the infirmary and entered, though she hated the place. The smooth tile floor was cold beneath the soles of her bare feet, and the smell of disinfectant and blood was sharp in her nostrils. The awful little room reminded her of the Academy, with its blue walls and blinding fluorescent lights and sharp needles and pain—lots and lots of pain. But Simon was there, so that made it alright, at least for a little while. As long as her brother was there, she could forget, and it became just another room, just another random point in spacetime.
He was alone, busy cleaning up, putting away shiny sharp instruments in their little plastic cases. He was in his pajamas. Presumably, they had taken the bullet out. She'd wanted to see him earlier, but they'd stopped her, said that she shouldn't be in the room when they did it, didn't want her to see her brother's blood, spattered red and glaring against all that white. They said her brother wouldn't have wanted her to see him in pain. Stupids. She'd already seen him in pain. Already felt him in pain, actually, felt the bullet when it pierced his leg, low in his thigh. That was why she'd screamed, a high, horrified shriek that resonated over Serenity's comm system, echoing within the recesses of her metal soul. River wondered idly where the bullet was now. Gone, she supposed, just a bit of trash destined to become so much spacedust. Funny how a little bit of lead could cause all that trouble.
Simon didn't notice her at first, though he didn't appear startled when he turned and saw her standing there, just blinked, consciousness readjusting itself to her presence. "River."
"Let me see it," she ordered. He rolled his eyes at her but required no further prodding, hiking up his pant leg to show River the gauze bandage wrapped around his lower thigh. White. There was a bit of blood on it, but not much; like a tiny red flower. "Did it hurt when it came out?"
"Nah," he dismissed, legging the pant leg fall. "I was so doped up on painkillers when Zoë did it that I barely felt anything." River gazed at him for a moment, waiting for him to say something more, but Simon merely gazed back. Silence stretched between them, blank and oppressive as the white walls of the tiny room, like the infinite vacuum of space. How long they stared at each other, exactly, River couldn't tell. Her concept of time was fuzzy. Entire empires rose and fell, rose and fell. Simon blinked.
"You're an idiot, you know," she stated loudly into the infinite vacuum of space. Simon blinked again, and River could see her insult crashing into his comprehension with the same variety of infinitely calm, languid inevitability with which celestial bodies collided into one another.
"Well," he said slowly, "I could probably say the same about you, after what you tried to do today."
"But that would be mean," River injected lightly. Simon frowned, and she could practically hear his entire train of thought screeching to a halt. Poor Simon, she thought absently; how difficult it must've been for him, having thought patterns that relied on such burdensome things as logic and consistency.
"What would be mean?" He inquired distractedly.
"Calling me an idiot," she replied.
"Oh," he said, mildly surprised. "Sorry." River smiled a pleased, wicked little grin, much like that of a cat playing with a mouse.
"Idiot," she denounced.
"Dummy," Simon shot back, not missing a beat.
"Slack-jawed, mouth-breathing fool," River declared, grinning madly. Simon folded his arms over his chest and molded his expression mockingly into one of deep contemplation, staring meditatively into space for a moment.
"Hmmmmmmm," he hummed thoughtfully for effect. Seemingly unable to produce a suitably witty—or suitably immature—insult for his sister, he lunged at her suddenly. River gave a little scream, dancing away from him, turned swiftly and burst from the infirmary shrieking with laughter.
She ran, fully aware that her punishment for toying with her brother would be swift and merciless. Her light, barefooted steps reverberated pleasantly against the surface of Serenity's cool, welcoming metal interior. River could feel the hum of the ship's engine and the heartbeats of its crew through the soles of her feet, could hear the soft, dull footfalls of her brother not far behind her as she dashed through metal corridors, laughing for joy. She snuck a glance over her shoulder and caught the manic grin on Simon's face as he gave chase, and soon his laughter joined hers. Together their laughter filled up the empty, rusty metal corridors as they sprinted through the dining hall, then the cargo bay, as River leapt off iron balustrades and clambered over wire mesh catwalks with Simon in hot pursuit, slipping breathlessly from her brother's grip just as he was about to catch her. Their pure childlike laughter filled Serenity with light until it was not rusting metal that their bare feet pounded upon as they ran, but damp earth after a rainfall; until it was not the ship's cargo that River crawled over and Simon crouched behind, hoping to ambush her, but rocks and tree trunks; until everywhere River looked was awash with rainbows, a forest of light where fallen leaves crunched beneath her feet.
At one point, the captain poked his head out of the door to his quarters long enough to shout, "Hey, you damn kids, some of us is trying to sleep!"
They ignored him.
Eventually their chase came full circle and they ended up in the same area in which they had started. River darted into their quarters and collapsed on her bed, where Simon tickled her until she quite literally shrieked for mercy. The forest melted away around them, and patches of the ship ebbed back its place, until all that was left was the dimly lit room that they shared. Simon sat on the edge of her bed and rested his hand on River's stomach, grinning, as they both caught their breath, and he gazed at her for a long moment in the dim light. River gazed back silently as her heartbeat began to slow, a wave of fatigue washing over her unexpectedly, her limbs becoming suddenly leaden and tired as the aftereffects of their game caught up with her. Simon gently threaded his thick fingers affectionately through his sister's dark brown hair. River blinked lethargically. "Did you really think," he murmured, "That after busting you out of that god-forsaken Academy and coming all this way, I'd really just sit there and let you hand yourself over to the Alliance?"
River became aware of her eyelids wanting to drift shut. "I was counting on it," she replied sleepily, suppressing a yawn.
"Well," Simon said consideringly, "I think we may have already established this, but you're a dummy."
River thought about giving Simon's mind a poke to see what her brother was thinking—see if he was having any regrets—but then decided she was too tired. "You could have been happy, you know," she said quietly, allowing her eyelids to slide partway closed as the soft comfort of sleep enveloped her. In her hair, her brother's fingers felt warm and good. "You could've been happy, if you'd just let me go."
"Oh, mei-mei," Simon said gently, his voice sounding oddly choked. "I am happy."
"Then why are you crying?" She wondered aloud, but before Simon could reply, River had fallen fast asleep.
Author's note: This oneshot is part of my quest to bring more Simon and River sibling cuteness to the fandom. I think this is one of my favourite things that I've written maybe ever, so your feedback is both welcome and very much appreciated. Thank you for reading.