Honestly, Daryl does have his little moments of joy; they're small and quiet and they don't always show. You'll catch more of his smiles watching his eyes than his mouth. This... is something different, though not entirely so. It isn't just the physical act, it's the closeness that has gotten them to this point, the triumph that they're alive and whole enough, in spite of everything, to care. They have every reason to be joyous, they would even if she wasn't tracing her fingertips along him, purposeful and deft. He's given up trying to stay still because he can't, because she seems to enjoy his reactions so much. Christ, can he get his mouth back on her without having to move?

He frees a hand from under her shirt to run it through her hair, setting his palm between her shoulder blades when she kisses him, holding her close, pressing himself against her wherever he can. It's not the frantic desperation that guided him earlier, but this time she certainly can't have any grounds to doubt whether she's distracting him enough.