Somehow, Dean's figuring the same exact thing.

The press of Lucifer's hips only helps matters. Though having his cock gently pressed towards him is moderately intimidating, there's little he can do to keep a grip without his hands. It makes it that much easier to keep him where he needs him, humming silently in the back of his throat to pass along the vibrations. Dean still focuses on bobbing his head slowly, his tongue passing smooth along Lucifer's length, stroking with every pass.