Holmes rises to Watson's challenge, kissing him hard in return, all too happy to do so, to know that Watson is an equal partner in this and that -- well, to be crass, that they'll be enjoying each other tonight more than he thought they would. That is always a pleasant surprise.

Eagerly he finishes unbuttoning Watson's shirt; he knows of Watson's injuries from the war, of course, but they're the farthest thing from his mind now, distracted as he is by Watson's lips and the feel of his skin. He pushes the fabric aside so that he might hungrily and possessively run his hands over him, exploring the landscape of new information available to him.

The only thing that could lure him away from Watson's mouth is the promise of discovering Watson's chest, so he frees himself from the kiss, intending to lavish some attention a little lower.

And then he sees the map of scars on Watson's shoulder. It's almost akin to a punch to his gut -- not because they're disgusting, or repulsive, but because they are the remains of what must have been an excruciatingly painful experience.

Closing his eyes, he leans down, beginning to kiss tenderly at the skin.