Sans shudders a little with something other than pain at that kiss. He's not at all sure how to feel about that promise, and not in any position to expend much strength wondering. He knows she'll be back, though. Grune is much better at making promises than Sans is.

He'll be where she left him, and even in the dark, he'll be easy enough to find - the sound of breaking bones, pained gasps, and stammering growls carries even through the trees.