His hand was moving of its own accord, finding its way on Sherlock's thighs and then cupping his quickly growing bulge, massaging it softly through his trousers. He remembered a few things about his past, before meeting Sherlock, but sex was not one of them. He had no idea what to do, and even though his body seemed to move on his own, he began to worry whether he could pull this through at all.
As he looked at the other's body, as he felt him move, he couldn't help but wonder how it was that they usually did it, but he was scared of asking, afraid it would put Sherlock off. He couldn't ruin this, it was too important.
"Can I undress you?" He muttered, deciding to start from the basics.