He's noticed both or either on other people, in passing, merely images filed away for later or discarded. But he's kept himself so separate from his own human wants for so long that any kind of preference is new.

Sherlock knows he wants to explore every inch of Molly before he makes up his mind which parts he likes best.

Her sigh lets him shift her a little--enough to lean her back slightly so he can fit his mouth around one hard nipple. One of his hands trails down her side and over her hip, down to the fly of her trousers.