Maria snorted softly to herself and typed instead: Timeline search — new parameters.
The monitor flickered, cycling through coordinates, and she leaned forward, elbows on the console, chin in her palm. The Ark hummed around her, that familiar low vibration she'd known since she was a girl, and the screen began to resolve into an image.
A house. Suburban. Texas, by the look of the flat-roofed architecture and the heat shimmer rising off the street. A two-story with a porch swing and a minivan in the driveway. Maria raised an eyebrow. This was not her usual fare—she preferred the exotic, the alien, the strange. But the dimensional scanner had locked onto something, and she'd learned to trust it.
The image sharpened, and the camera moved inside.
Two kids. A boy and a girl, both around thirteen, both with the same dark hair and the same stubborn set to their jaws. Twins, clearly. The boy was thin, angular, wearing a button-up shirt with a bow tie that seemed to be strangling him. The girl had a tank top on, and even at a glance, Maria could see the reason the scanner had flagged this timeline.
The girl's chest was—well. There was no polite way to put it. She had breasts that belonged on a girl five years older, full and heavy, straining against the thin fabric of her tank top in a way that made Maria's own pregnancy-swollen chest ache in sympathy.
The boy was pacing. His name, according to the readout in the corner of the screen, was Sheldon. The girl was Missy.
"This is a disaster," Sheldon announced, his voice pitched high with distress. "A biological catastrophe. My own body has betrayed me."
Missy rolled her eyes from where she sat on the edge of his bed. "Sheldon, it's not a catastrophe. It's just—"
"An erection, Missy. An involuntary engorgement of the corpus cavernosum, triggered by—" He gestured wildly at the air. "—by what? By nothing. I was calculating the trajectory of a tennis ball. There was no stimulus. No visual, no tactile, no—"
"You were watching that girl from next door mow the lawn in her bikini top."
Sheldon froze mid-pace, his face going red. "That is—that is an entirely unrelated observation."
Maria chuckled softly, her hand drifting down from her belly to the waistband of her pants. She settled deeper into the chair, her thighs parting slightly, and watched.
"Sheldon, you're a boy. Boys get hard-ons. It happens." Missy crossed her arms, which had the effect of pushing her breasts up even more, and Maria saw the boy's eyes flick down, then away, then down again. "It's not a big deal."
"It is a big deal! It's uncomfortable, it's distracting, and I don't know how to make it stop!" He gestured at the tent in his pants with a look of pure horror. "I've tried ignoring it. I've tried thinking about calculus. I've tried—" He shuddered. "—cold water. Nothing works. It just stays there. Throbbing."
Missy sighed, a long-suffering sound that seemed far too world-weary for a thirteen-year-old. "You really don't know what to do about it, do you?"
"I know the theory," Sheldon said defensively. "I've read the literature. But the practical application—" He gestured at his crotch again. "—has proven… elusive."
Maria watched Missy's expression shift. There was something there, something that flickered behind her eyes, a calculation that didn't match the bored teenager act. The girl's gaze dropped to her brother's straining pants, then rose to his face, then dropped again, slower this time.
"I could help you," Missy said quietly.
Sheldon blinked. "Help me? How? Unless you have a textbook on practical urology in your room, I don't see—"
"Not a textbook." Missy stood up, and Maria saw the way her fingers twisted together, nervous and determined at once. "I can show you. I know how it works. I've—" She bit her lip. "I've figured it out. On my own."
Maria's hand slipped fully into her pants, her fingers finding her clit, slick and swollen from the earlier viewing. She watched the screen with rapt attention as Missy stepped closer to her brother.
"You've what?" Sheldon's voice cracked.
"I've touched myself," Missy said, her cheeks flushing but her voice steady. "Girls do it too, Sheldon. We have our own version of this problem." She gestured vaguely at her own body. "And I figured out how to fix it. I can show you. If you want."
The silence stretched between them, thick and electric. Sheldon stared at his sister, his mouth opening and closing like a fish, and Maria could see the war happening behind his eyes—the scientific curiosity warring with the social conditioning that told him this was wrong.
"The literature," he finally said, his voice barely a whisper, "suggests that masturbation is a normal and healthy part of adolescent development."
"Yeah. It is." Missy took another step closer. "But that's not what I'm offering."
"What are you offering?"
Missy reached out and took his hand. She guided it to her chest, pressing his palm against the swell of her breast, and Maria heard Sheldon's sharp intake of breath through the monitor's speakers.
"I'm offering to show you something better than your hand," Missy said softly. "If you want to learn."
Maria's fingers moved faster between her legs, her breath coming in soft pants as she watched the boy's hand tremble against his sister's breast. The taboo of it, the wrongness, was like a current running through her, and she felt her own body respond, her hips rocking against her fingers.
Sheldon's voice, when it came, was hoarse. "How do we—how does this—"
"Just follow my lead," Missy said. "And try to remember you're my brother, so I don't have to teach you the same thing twice."
She pushed him back onto the bed, and Maria watched with her hand between her legs as the girl climbed over the boy, her tank top riding up, her heavy breasts swaying with the movement.
"First," Missy said, her voice dropping into something husky and sure, "we need to get these off."
She unbuttoned his shirt with practiced ease, pushing it off his shoulders, and then her fingers found the waistband of his pants. Sheldon's hips lifted instinctively, and she pulled them down, his briefs following, and his cock sprang free—hard, flushed, already leaking at the tip.
Maria's breath caught. The boy was well-endowed for his age, long and thick, and she imagined she could feel the heat of it through the screen. Missy seemed to think so too, because she stared at it for a long moment, her lips parting.
"Wow," she breathed. "Okay. That's—that's bigger than I expected."
"Is that—is that a problem?" Sheldon's voice was strained.
"No." Missy shook her head, a smile curling at the corner of her mouth. "No, that's not a problem at all."
She wrapped her fingers around the base of his cock, and Sheldon gasped, his hips bucking off the bed. Maria felt her own cunt clench, her fingers sliding through her slickness, and she watched with burning eyes as Missy leaned down.
"I'm going to show you what it feels like to be inside a mouth," Missy murmured. "Just try to relax. And tell me if I do something you like."
She took him into her mouth, and Maria's hand stilled for a moment, watching the girl's lips stretch around the boy's shaft. Sheldon's head fell back, a low moan tearing from his throat, and Missy worked him slowly, her head bobbing, her tongue curling around the length of him.
"Oh," Sheldon gasped. "Oh, that's—that's—"
"Good?" Missy pulled off for a moment, her lips slick with spit. "I can go faster."
"Yes. Please. Faster."
She took him deep, her throat opening, and Maria watched the boy's hands fist in the sheets, his whole body arching off the bed. The sounds he made were raw, animal, completely unlike the precise, measured boy who'd been lecturing about corpus cavernosum minutes ago.
Maria's fingers moved frantically now, her hips grinding against her hand, and she could feel her own climax building, a hot pressure coiling low in her belly. On the screen, Missy was taking him deeper, her nose brushing his pelvis, her throat working around him, and the boy was babbling, incoherent, begging.
"I'm going to—I think I'm going to—" Sheldon's voice broke. "Missy, I'm going to—"
Missy pulled off just in time, her hand pumping his shaft, and the boy came with a strangled cry, ropes of cum arcing across his stomach, his chest, his face. Maria watched it happen, watched the girl's hand milk every last drop, and felt her own orgasm crest, her body shuddering against the chair.
She came with a gasp, her thighs clamping together, her fingers pressed hard against her clit as the waves rolled through her. On the screen, Missy was crawling up her brother's body, her mouth finding his, and Maria saw her taste herself on his lips.
"That," Sheldon said, his voice wrecked, "was the single most extraordinary experience of my life."
"We're not done yet," Missy said, and there was something new in her voice, something hungry. "I told you I'd show you something better than your hand."
She sat up, straddling his hips, and reached down to pull off her own shorts. Sheldon's eyes went wide as she revealed herself, and Maria saw the boy's cock, which had barely softened, begin to stiffen again.
"You want to feel what it's like to be inside me?" Missy asked, her voice soft. "To fill me up?"
"Yes," Sheldon breathed, and there was no hesitation in his voice now. "Yes. Please."
Missy positioned herself over him, and Maria watched, transfixed, as she sank down, impaling herself on his cock with a slow, shuddering sigh. Both twins moaned in unison, and the boy's hands flew to her hips, gripping her hard.
"Oh my god," Missy gasped, her head falling back. "Oh my god, Sheldon, you're so—you're so deep—"
"This is—this is incredible," Sheldon managed, his voice strained. "The sensation is—the feedback loop of the friction against the—"
"Shut up and fuck me," Missy said, and she began to ride him.
Maria watched, her hand still between her legs, her body trembling with aftershocks, as the girl bounced on the boy's cock, her heavy breasts swaying with each movement. Sheldon's hands came up to cup them, his thumbs finding her nipples, and Missy moaned, her rhythm faltering.
"Yes," she breathed. "Touch them. Squeeze them. They're—they're so sensitive—"
The boy obeyed, his hands kneading her breasts, and Maria could see his hips starting to buck, meeting her movements, his own pleasure building again. The sounds of their bodies filled the room, wet and obscene, and Maria felt her own body stirring again, her fingers sliding back to her clit.
"I'm going to come," Missy gasped, her movements growing frantic. "Sheldon, I'm going to—"
"Wait," he said, and there was a command in his voice that surprised them both. "Wait, I want to—I want to try something."
Missy stilled, her chest heaving. "What?"
"I want to—" Sheldon sat up, wrapping his arms around her, and Maria watched as he carefully shifted their positions, laying her back on the bed. "I want to see your face. I want to watch you come."
Missy's expression softened, something tender flickering behind her eyes. "Okay," she whispered. "Okay."
He pushed inside her again, slow and deep, and Maria watched the girl's back arch, her mouth falling open. The boy moved with a rhythm that was almost scientific, measured, deliberate, but the effect on his sister was anything but clinical. She was writhing, moaning, her nails raking down his back, and Maria could see the exact moment she came, her cunt clenching around him, her whole body shuddering.
"Sheldon," she gasped. "Sheldon, I'm—I'm coming—"
"I can feel it," he breathed, his eyes wide with wonder. "The contractions—the rhythmic muscular spasms—"
"Stop talking like a textbook and fuck me," Missy snarled, and she wrapped her legs around his waist, pulling him deeper.
The boy complied, his rhythm quickening, and Maria watched, her fingers flying, as he drove into her, his own climax building. The girl's arms came around him, holding him close, and she whispered something in his ear that the monitor couldn't quite capture.
"I'm going to come inside you," Sheldon said, and it wasn't a question. "I want to—I want to fill you up."
"Do it," Missy breathed. "Do it, Sheldon. Come inside me. I want to feel it."
He buried himself deep, and Maria watched his body shudder, watched the girl's eyes roll back, and she felt her own orgasm building again, a second wave cresting. On the screen, the boy collapsed onto his sister, their bodies slick with sweat, and Maria could see the cum leaking from where they were joined, the evidence of what they'd done.
She came with a cry, her body convulsing in the chair, and for a moment the room spun around her. When she could breathe again, she looked back at the screen, where the twins lay tangled together, breathing hard, the boy's hand resting on the girl's stomach.
"That was—" Sheldon started.
"Don't say it," Missy said, but she was smiling. "Don't you dare say it was a 'fascinating biological experiment.'"
"I was going to say 'life-changing,'" he said, and there was something soft in his voice. "But 'fascinating biological experiment' works too."
Missy laughed, and she kissed him, soft and sweet, and Maria watched them with her hand resting on her belly, feeling Rift's child kick again.
The monitor hummed, and she reached for the keyboard, her fingers trembling with a pleasant exhaustion.
Timeline 7792 — Sheldon & Missy Cooper. First time. Full lesson administered.
She typed the last line, then paused, a thought flickering through her mind. The scan had flagged this timeline for a reason. The girl's body, the brother's curiosity, the way their pleasure had fed each other—there was something there, something the dimensional currents had wanted her to see.
Maria leaned back in her chair, her hand still on her belly, and let herself wonder what else that timeline might hold. The boy had learned one lesson. But the girl—the girl had looked at her brother's cock with a hunger that suggested she wasn't done teaching.
The monitor flickered, the image of the Texas bedroom fading to static, and Maria smiled, a slow, knowing curve of her lips.
Somewhere in the vast machinery of the Ark, another story was already beginning to unfold.