It's not till she's about to draw level with him that the penny drops and the thought completes itself: her eyes are frightened. Frozen hard as iron and sharp as glass; he knows the temper of it. This dowdy little girl is one of the most dangerous things for a mile around, and she's gut-deep afraid.
Makes perfect sense. So is he.
He turns away from the window, unhurried, timing it so that he has her in direct view as she passes him. Says, to the back of that bright head: "Who's after you?"
His voice is low, but he can't manage soft, though he'd like to; it comes out a rusty creak, and he winces a little.