Continuing to meet Lucifer's thrusts would be a good start. Along with tightening around him. Not to mention letting himself get lost in the feelings Lucifer is giving him instead of feeling guilty about enjoying it or inclined to be difficult.

"That's it. Be an active participant instead of just laying there and taking it." Lucifer comes only a few thrusts later, filling Dean yet again although he keeps snapping his hips forwards to drive himself in.