She may be slightly blurry so close to him, but Sherlock finds he has to watch what Molly's face does when his finger presses up and in. It's a sight that makes it difficult for him to breathe. There's something close to genuine ecstasy in her expression for a second, there and gone, a glimpse of pleasure an order of magnitude greater than he's seen on another human being. And the sound she makes is gorgeously unrestrained, yet another surprise.

He had no idea anyone could do this to Molly.

He's glad he gets to find out how wrong he was.

(And he had no idea having sex could be this fascinating. He's glad she's showing him how wrong he was about that, too. Never let it be said Sherlock Holmes doesn't learn from his mistakes.)

Her hips push forward, into his hand. It's not easy following her movements while her hand is still on his cock, but he manages, thumb flicking over her clit, forefinger sinking deep.