Greg was only more encouraged by the way Theo was reacting. He bent lower on Theo, going for the space between testies and ass, and he licked up, stroking the growing stiffness. He was pleased by the mewing noises, sounds Theo used to make, and Greg used his mouth more, sucking and licked, massaging and squeezing.
His destination was lower still and he finally got there, finding Theo very clean. Greg put his hands onto Theo's legs, encouraging Theo to curl up, opening himself to Greg's mouth better. That puckering spot was what Greg wanted to maul; his tongue stroked and licked before he began to invade it with just the tip.