The siblings huddle together in the confined space, their bodies pressed close, their breaths ragged. Michelle's hand trembles as she reaches out, her fingers tracing the outline of her brother's erection through his pants. He shudders, his eyes closing briefly, before he looks at her, his gaze intense. "We shouldn't," he whispers, but his body betrays him, his cock throbbing against her hand. Michelle bites her lip, her heart pounding, before she makes her decision. She unzips his pants, reaching inside to pull out his cock. It's huge, throbbing and leaking pre-cum, a testament to his desire. She looks up at him, her eyes filled with a mix of fear and lust, before she tentatively takes him in her mouth, her tongue swirling around the head, tasting him for the first time.