Fuck his ass...

You grab him by the neck and throw him in the bed, the pulls his legs and hips over the edge. Spreading his asscheeks, you bury your face inbetween them and shoot out your tongue into his asshole. He exclaims in both surprise and pleasure. "Ah, gods! How are you doing that! Never mind, just keep doing that."

You find something called the prostate and wrap your tongue around it before giving it a good squeeze. William starts jerking his cock while praising your "divine" tongue. If only he knew...

After about a minute, William cums on the floor. Now his ass is just begging to be fucked. You kneel behind him and place your cock at his asshole. Its puckering out, as if its trying to kiss your cock. Not one to dissapoint, you ease your cock into his welcoming ass. "Now this, is a really good ass."
"Thank you, gah, Sir."

William takes your entire cock up his ass with ease, maybe you should make it a bit bigger. Or you could just move on to fuck him hard like you fucked his mother...