With his resting face pretty much a frown Sarge doesn't look too friendly and welcoming by default, unless he puts some real effort in it that he generally doesn't want to make. But now he finds himself squinting at the boy because it dawns on him that what he has been through is more than just the regular good old surviving in a world turned to shit. It actually hits him in the head quite violently and for a moment he deeply regrets leaving on his own. Because this is way too much for him to handle.
The kid sits there nursing the water bottle like a child and staring at him to a point where he feels like bolting. Not that he could run, not with the state his lungs are in. Still, he keeps trying and all it would take is a quick little dash around the next corner. If there is one thing Sarge knows it's thoroughly fucked up people, takes one to spot one and all, but for once he is willing to bet that what he has been through absolutely pales in comparison. "You think you can walk?" Because there is no way he can leave that kid here, that's nothing he wants to add to the laundry list of guilt that keeps him awake most nights.