And now a bit of comment porn for you (although it's more comment than porn)...
"Kneel," Severus commanded, and Harry dropped to his knees.
The older man walked around his pet, admiring the boy's discipline. For years he had yelled at Potter, trying to teach him something, anything, but to no avail. Now, Potter hastens to do his bidding. Who knew that Severus should have been using his mouth for something other than scorn? One blow job and the boy was putty in his hands.
"You have been exceedingly obstinate today, Pet," Severus said. "What do you have to say for yourself."
Harry raised gleaming green eyes to his Master.
"I deserve to be punished, Sir," he replied.
Severus saw the challenge in Potter's eyes, daring him to prove himself worthy of Harry's submission. He grinned ferally.
"Yes, you do, Boy!"
Severus unzipped his pants and pulled out his rapidly swelling erection.
"Suck!" he commanded.
Harry went to work. Tentatively, he darted his tongue out to taste the tip. Smiling in appreciation, he licked his way around Severus's cock. He pulled back the foreskin with one hand while the other massaged Severus's balls. The older man groaned in appreciation. His Harry was becoming quite proficient at seduction.
Harry kept teasing him, tasting his cock but never putting it completely in his mouth. Severus became impatient with his pet's behavior.
"Stop teasing and get to work!"
Harry smirked and Severus wondered what he was up to. Then Harry opened his mouth wide and swallowed Severus whole. Severus was unprepared for the onslaught of sensation and almost came right then.