Dean braced his forearms on either side of Sam's hips and just stayed in place, letting Sam thrust up into his mouth however he liked. Sam never went crazy with it, so he didn't worry about it being too much.

He continued to suck hard while Sam's cock was sliding back and forth across his lips. Kept it going while his brother came and after Sam settled back, spent. He settled back down deep, sucking soft and easy at the softening length.