He let's you go for it

He just nods without saying a word.

You giggle again and then start working up and down on his shaft. It is already slick with moisturiser or lube so it isn't hard to slide your hand up and down.

Peter leans back and just groans in satisfaction - you guess that it is his first time with something other than his own hands.

I've already fucked Emily and her mom, so why not her brother? Your mind encourages you.

You start jerking him faster, spitting on your other hand, you add that to the mix. You can get it around the circumference, but your two hands don't cover the full length.

"Ooh," You say. "Are you going to cum for me?"

Still with his eyes closed Peter nods.

You look back at Emily and are not surprised to see her casually playing with herself.

You give her a wink.