Shepard gave a little shake of his head when she made the demand. Don't stop. "Alright." He pushed himself up. Drawing his knees right up against her ass. He shifted her hold on his ass by shifting her feet up over it.
And with the angle changed, he thrust all the way into her, hard enough for his thighs to clap against her backside. Like jumping in a pool, sometimes you had to do it all at once.