Can Sarah keep her urges in check?

When Sarah looked back over her shoulder, she saw her brother standing frozen in the bathroom door. Sarah stared back at him, feeling embarrassed by his attention. Yet at the same time, she felt strangely aroused, and she could feel her cock giving a twitch. It was still rock hard, and felt warm against her stomach and the under and inner sides of her breasts. She had been almost ready to explode before she had been interrupted.

She could see that her brother enjoyed the look of her body. His eyes roamed all over her exposed backside, his expression longing and lecherous towards her. Sarah didn't understand how he could lock at her like that. "He is my brother!" were her thoughts. But his arousal was written all over his face, staring at her, with his mouth wide open. Yet, when she looked at his body for the most obvious proof of his lust, she could not detect any buldge in his pants at all.

Though that particular thought was quickly cleared from her mind, as other images and impressions came back to her and pretty much flooded her mind:
How all those weeks ago, Amy had fucked Carl into his ass relentlessly with a big strap-on, and how he had screamed in pain and pleasure. Images from her dream, where incredibly busty and sexy futanari cheerleaders used their cocks to slap the faces of the male football players, until the cheeks were red and tears of pain streamed down their faces. Only for the futanari cocks to to enter their mouths balls-deep a few moments later.

She looked back up at Adam, who still hadn't made a move. Another thought entered her mind: She could step out of the shower, end this charade and ram her thick fuckstick violently right into her brother's wide open mouth. "Fuck!" Sarah groaned in arousal and frustration. She couldn't control herself. Her cock twitched again, and she could feel her orgasm approaching.