...Hearts tend to ache. Heavy burdens and all that.

[He licked his lips, watching the detective drum out a rhythm over the muscle in his chest they were discussing.]

Look, Sherlock... I can't exactly make promises without knowing what's going on but... I'll keep that in mind when the time comes.

[He reached out and pressed a pair of fingers over Sherlock's tapping hand, stilling it momentarily against the detective's chest.]

So... even if I know you don't lack a heart, I'm not out to prove it and I'm not looking to cause yours any more strain the need be. Okay?

[After a short, pointed look to impose his sincerity, the doctor eventually draws his hand back, clearing his throat.]