Compliment her enthusiasm and apply the one bar prison.

Theo smiles approvingly at Kelly's words. "That's the spirit," he says, moving closer with the one bar prison. "Just relax and let me guide you."

Kelly's breath quickens as Theo positions the device beneath her. She feels the cool touch of the dildo against her entrance, causing her to shiver. Slowly, inexorably, Theo lowers her onto the shaft. Kelly gasps as it enters her, stretching her walls. The sensation is overwhelming - a mix of discomfort and unexpected pleasure.

"Spread your legs," Theo instructs firmly, guiding her feet apart. Kelly complies, sinking further onto the dildo. She whimpers softly, overwhelmed by the fullness.

Theo efficiently secures her ankles to each end of the spreader bar. The click of each cuff closing sends a jolt through Kelly's body. She tugs instinctively, but finds herself completely immobilized - legs spread wide, impaled on the unyielding shaft, unable to lift herself off or close her legs.

Kelly's entire body trembles, a cocktail of fear, arousal, and vulnerability coursing through her. Her earlier bravado has evaporated completely. "Oh god," she breathes, her voice shaky. "I've never felt anything like this."

She squirms slightly, testing her bonds, but every movement only serves to shift the dildo inside her, sending sparks of sensation through her core. Kelly bites her lip, fighting back a moan. Despite her nervousness, she can feel her arousal building, her body betraying her with its enthusiastic response to the stringent bondage.