Jeph's been asked this before... on his "About" page, there's an interview. Among the questions:
Are your characters based on real people or events?
No, they spring entirely from my own imagination. Sometimes they will espouse opinions that agree with my own, but there the similarity to real-life pretty much ends.
Mind you, that doesn't preclude him from adding another answer below (in fact, I'd be interested in hearing more about his character-creation process), but I thought that I'd be helpful and throw that on the board.
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One thing I was wondering regarding characters is this:
How many characters is too many? Personally, I don't find QC hard-to-follow or anything, but there are TONNES of characters if one thinks about it:
(sorry that I'm not hardcore enough to remember some of the minor character's names)
FAYE
DORA
THAT BLONDE COFFEE-SERVER
THAT TRUCK-DRIVER TURNED NOVELIST IN THE BAR
STEVE
ELLEN
NATASHA, ellen's roomie
VICKY
PINTSIZE
PINTSIZE'S FEMALE COMPANION
etc etc
and Marten of course
And that's not even all of them.
Of those, at least THREE new characters have been introduced in the past few weeks.
1) I'm just wondering if Jeph ever feels any pressure to
avoid creating a new character to avoid confusing people.
2) If he ever has any feels any pressure to make sure the strip revolves around Marten or include him in some way even if Marten is sometimes not really the "main" character in a plotline.
I ask because I also run a comic (not as well-read as his perhaps) that has a cast of 9, and I regularly run into these dilemmnas myself. It would be interesting to get another perspective.