"Jamie, do you trust me?" Jeff licked his lips, his heart beating at the thought of what he was about to do.
"Of course I do, Jeffy." She smiles and wraps her arms around her brother at the mention of her name.
"Ok..." Jeff says, shivering with nervous excitement, "Ok then..."
Jeff lays his sister back against the couch and pulls her dress up over her head and throws it to the floor at his side. Her naked, amazingly matured body is almost enough to send him over the edge. Her breasts are perfect, her body has curves in all the right places and the fully developed slit nestled between her legs is one of the most beautiful things Jeff has seen in his entire life. His cock is rock hard and straining against his jeans when he unzips his fly and lets it bob out into the open air. Jaime stares wonderingly and points to the hard shaft between his legs, "What's that, Jeffy?"
Jeff gulps and forces a smile, the wrongness of the situation pressing down on him like a heavy blanket, "It's my penis, Jaime."
"Oh... what's it for?" She reaches down and grabs his length, he almost comes right there, shuddering and gasping.
"Ah! It's... for sex..." He manages through gritted teeth.
"What's sex?"
Jeff moans and reaches up, cupping one of his sisters breasts, pressing his thumb into the hard nub of her nipple. The sensation causes a moan of her own to escape past her small pre-pubescent lips. "I can show you." He smiles, imagining the fiery corner of hell he'll most likely end up in.
Jeff gingerly pulls his sisters hand from his penis and places it at her side before grabbing her hips. "What are you doing?" She looks nervous. He offers her a reassuring smile and then moves forwards, pressing himself into her.
Her face seemed to light up then melt at the feeling of his cock inside her and that was all Jeff needed to keep going. Slowly he began to pump into her, his hips rolling, sliding his manhood in and out of her moistening sex with an ease that surprised him. As he bucked and humped his hands moved up to her glorious DD cups and began to knead and grope at the soft flesh, tweaking and pinching her erect nipples.
"Jaime, Jaime, Jaime" Jeff gasps between thrusts, getting his sister to lean forwards and wrap her hands around her brother and pressing into him even as he continued to press into her.
The siblings became totally lost in their pleasure, thrusting and humping and groping. Jaime was the first to cry out, and Jeff quickly followed, breathing in sharply as he came into her, his seed mixing with her juices on the couch bellow them.