(Tentative writeup; feel free to modify)
A tall, lanky young man with short blond hair and watery blue eyes. He looks to be somewhere in his twenties, yet sometimes gives off an air of a much older man. He also seems to be vaguely British, but that too is hard to say for sure. Still, he is rather unflappable. He's usually dressed in a janitor's uniform and wields a mop. He's deadly with it... or so some of the younger kids say, sometimes. Also, he is known to able to move almost noiselessly and appear seemingly out of nowhere, but maybe it's just his janitorial aura.
When the pilots found the base, the man who called himself Nathan Jones was already there. It's hard to say anything else about him.
Enigmatic. He's a man of few words - which he mostly uses to give off cryptic, but useful warnings and advice, or to softly, but firmly reprimand people for littering or making an unnecessary mess. He appears to take his janitorial duties very seriously. At the same time, he is fairly kind and helpful to those who have no one else to turn to, in his way, and has been known to provide sage advice that more than anything else makes him seem older than he is.