It's hard to write about Bill (it's only William if you're nasty) because Bill is a great writer. He would argue that this isn't the case, and while that humility certainly makes him a better person than some, it isn't true. Ask any author about what makes a good writer and I'll bet all the money in my pockets they'll say something like, "Someone who actually fucking writes."
Saying you're a writer is easy, it's the writing, the torturous painful words on the goddamn page that makes you a real scribbler, and that Bill has in spades.
He is also a treasure trove of tropes, stories, and characters. He has a long and obvious love of narrative in all its forms: TV, film, novels, comics, and almost any tabletop RPG you care to mention. Bill can spin you a tale.
What he doesn't do is play many video games, so like the rest of us he's more or less fucked when jam weekend comes around.