It was day, well, kind of.
Because in the Underground "day" was just when the fake ceiling lights cranked all the way up around ten in the morning, somebody up there having apparently decided nobody would tell 10 from noon and dumped the same light on everybody.
Nash was running and his lungs were literally on fire. Twelve, maybe thirteen, you never really knew, because down here nobody had a real birth date and you changed age by feel.
The guy was skinny, actually too skinny, ribs sticking out under a wrecked T-shirt that had probably belonged to three people before him, sneakers holed and slapping the cracked concrete every step.
Kid body, but legs that already knew exactly where to land in the dark, the kind of thing school does not teach you and survival does, fast, if you do not want to eat pavement.
