Dean's body jerks like it's been hit with an electrical current when that last vibrator is turned on. The struggle and strain to remain as still as he could while it was being inserted is gone then. He twists and writhes, not bothering to try and restrain the sounds that are wrenched from him.

The question makes him gasp, gripping the chains and post tighter to anchor himself. "I don't know..."

It isn't something he's ever been asked to do. No one's ever mastered him quite so thoroughly. Certainly never so quickly.