The watcher
Well, as you know of me, I still haven't got the D20 Modern rules. But I'll post a background for my take on the watcher, and hopefully, Gwolf or Kit would like to munch on it. (if not, I can't get in, until I've downloaded the SRD, which isn't going fast, if at all.)
Gary Gray, Watcher
Age: 61
Proffesion: Teacher (Old English and Forgotten Languages/Cultures)
Gary, Or Mister Gray as he likes to be called, graduated from Cambridge in the days of the hippies. When on Oxford, he despised 'That filthy long-haired rabble' but he turned 360 degrees when he went to America for a year. During that year, he went all-out, partying, protesting, sexing up Hippie chicks, and all that. He was known as the only hippie ever to wear a tweed-costume.
When he left, he tried to fit in with the Bitish upper class, but couldn't pull that off because he was too 'free thinking'. Instead, he found other friends in the society of watchers. He became a member of the society, and generally changed back in the old stick-in-the-mud he was at college. He tried to forget his wild days in the US, and din't speak off it.
After some service in the society, he was sent to America, to act as a secondary watcher for the Slayer, because the chap that was there now, didn't seem quite capable to do the job (You know, that watcher that replaced Giles, Forgot his name though). After the Slayer disposed of that watcher, he began to get more interested in her free-spirited personality, which reminded him of his own wild past. After A while, he was officially appointed watcher of the Slayer, but he didn't act as one. He won the slayers trust in the guise of a teacher and didn't proclaim he was her watcher yet. The Slayer just sees him as the old friendly Teacher who happens to know a lot about monsters and stuff

D)
The Slayer and the watcher have build a very strong bond now, and work as a team.