It draws a long, gasping moan from Draco as Snape's lips catch on his erection, his tongue sliding against the tip and there's a shuddering exhale that shakes through his body. He's done this part before, at least; he's even well-behaved enough to not jerk his hips into the hot, damp press of the pleasure of Snape's tongue. It feels so good, and there's a brief, idle thought about returning the favor, later, on his knees, hands on Snape's hips and feeling the slide of his cock against his tongue... But, the thought is gone almost before it has a chance to settle, the press of Snape's finger, the way it curled inside him.

His back arche's, his fingers on Snape's shoulder pressing tighter. His body isn't fighting it quite as intently, the pleasure a suitable distraction, Draco's eyelashes fluttering, his gaze cast down his body, watching Snape with rapt focus. He pulls his finger back, only to press it back in, and Draco's eyes briefly close as his body tenses for a breath; by the next he has his composure back, and he's relaxing into it. His breath coming in rough gasps scattered with moans, his blue eyes dilated, pupils blown.