My Greg story is boring, and I wouldn't want it any different. To me he is (dare I say it?) just an npc, a minor boss at best.
Moonwood Mills used to be part of the mining empire of the McGavin clan. The clan's american branch is still influential, not to mention wealthy, but they've turned to other endeavors, so Moonwood Mills is abandoned. Greg's mom was the last foreman, she didn't want to leave the town and someone had to keep the rabble out of McGavin turf anyway. So next lots of plot that I cannot reveal yet in case I want to post the story here happened, leaving Greg a feral werewolf. He has no recollection of what has happened or that he used to be a human and is stuck in an endless present, feeling neither fear of nor wants for the future.
The important part is that so far there were no werewolves in the world. Now they are there, Greg was the first and one of my sims is directly responsible for this.
One year later:
Of all of this Logan McGavin only knows that pesky gangs have moved into Moonwood Mills. The situation is now at the point where Logan has no choice but to involve *gasp* outsiders. Fortunately one of my cop sims, the vampire Captain Reed, is a distant McGavin relative. Reed agrees to investigate in Moonwood Mills together with two other sims that conveniently don't have an occult state yet.