When I started S*P, all the characters were meant to represent a friend everyone had. Davan's the hard-to-like friend who, while trying, WILL be there for you. Aubrey's the friend who tests your limits. PeeJee is the friend who acts tougher than she probably is and cares a little too much. Scotty's the friend you lose and you never understand why.
The main character and Author Avatar, representing Milholland when he was a younger man. Davan is snide, sarcastic and takes most of life with an uncaring, unsympathetic nature, which often gets him into trouble. Still, he cares deeply for his friends and family, despite his cynical nature.
Randy's own words on the subject: "Near the end of the first year. I realized quickly I didn't want this comic to be autobiography. Even when it started, Davan wasn't who I was then - he was who I'd been a few years before and, I should add, someone I didn't like (I find it funny when detractors claim Davan is who I think people should be and is "cool" - it proves they've never spoken to me or done a bit of research. Davan's an asshole and a lot of the misery he's gone through, he brought on himself)."
Author Avatar: From a time in Randy's life when he was especially cynical and dreary.
Hard Drinking Party Guy: Back in the early days of the strip, he was much worse. He has stated that his combined German, Irish and Native America heritage makes it literally impossible for him to allow alcohol to be wasted.
Ignored Enemy: Ollie Pompey, the badly abused nephew of the late (and horrifyingly nasty) theatre director Avagadro Pompey, really, really hates Davan, to the point of wanting to destroy him. Davan hadn't realized this, and mostly found it pathetic when he found out.
Informed Deformity: Women in the strip used to react as if he was the ugliest human being alive, despite him being drawn in a rather ordinary fashion. This plays into his status as the Author Avatar—Randy himself doesn't like his appearance.
Kavorka Man: For an ugly dude, Davan has slept with upwards of six or seven hot women since the strip began ten years ago.
Law of Inverse Paternity: Played with; Davan didn't want to be Rory's father, but was at least willing to step up if he was, unlike the other candidate. Davan wound up becoming his Parental Substitute even after finding out he wasn't the dad, and admits that in retrospect he wishes he had been the father after all.
Troll: Especially when working together with Jason.
Vitriolic Best Buds: Pretty much the nature of the comic. They all prank and tease each other mercilessly.
Write What You Know: Davan used to work for MedicAid, doing the same work Randy did before his webcomic really took off- billing poor people for ambulance fees.
Penelope Jennifer "PeeJee" Shou
A Canadian girl who moved down to Boston to meet up with some online friends, PeeJee is a devoted pal to the others. She's much like Aubrey, but far more emotional and liable to feel sympathy, or the need to cry. Randy has stated that she represents "those friends who aren't quite as tough as they seem". One of her key early traits was a huge crush on gay cast member Jhim. Despite the vitriolic nature of most of the characters, they openly felt sorry for her.
Collector of the Strange: Her new hobby is looking for the most fucked up sites possible, having filled up four external hard drives worth of 'em.
Vanessa: I have seen suicidal notes less depressing than this.
PeeJee: Oh, really? Are there any suicide notes that mention cool sites involving Russian amputee mail order brides?
Vanessa: I dunno. Are there?
PeeJee: ...Yes. Sixty-three. They're on hard drive two.
Davan's best friend from childhood, and completely platonic. She's the devious schemer of the group, and rarely gets overly-sympathetic or mushy. She's based off of Randy's own best friend from childhood, anime voice actress Clarine Harp.
Write Who You Know: Anime voiceover actress Clarine Harp, herself one of Randy's friends from childhood in Texas.
Jason Chorde (né Pratchett)
A jovial fat guy who was an early acting friend of the gang, and stuck around in all later arcs. Probably the smartest of the gang, and most manipulative. He's the most committed to his schemes (such as the catgirl webcomic).
Troll: Especially when working together with Davan.
Write Who You Know: Jason is based off of one of Randy's friends from his acting days in Boston, who still runs part of his website.
An early recurring antagonist, Kharisma was a high-and-mighty actress with a love for money, and a hatred for the ugly little people (like Davan). After doing many horrible things to many people, she met with a few Pet the Dog moments by giving Davan some much needed advice about quitting his job. Then she got into a murder pact with Avagodro Pompey, got arrested, got broken out of jail, and now she's on the run with a possibly-real physic manifestation of annoyance called Fluffmodeus.
Character Development: Went from a stupid Rich Bitch to a more sympathetic (but possibly insane) fugitive, and has settled into a life doing sketchy odd jobs under the name Nancy in a vague rural location.
The Chew Toy: Said sketchy odd jobs include freelance collections agent/legbreaker and babysitter for stupid druggies. This is after getting framed for a murder she was going to commit anyway but didn't have a chance to, scorching her own face with an Aerosol Flamethrower, spending time in jail, and finding out that the benefactor that helped her out of prison was an anti-stuffed-animal-cruelty vigilante.
Sleeping with the Boss: Kharisma makes no secret that she'll sleep with anyone for advancement (and is later fired without ceremony when the boss' fetish goes from redheads to blondes), while Monette is accused of this by an older, uglier coworker.
Co-worker: At least all that lying on your back must have done wonders for your posture.
Monette: Well, seeing as your method gave you bad knees and rancid breath, I figured I'd do it differently.
Write Who You Know: Early Kharisma material was derived from a woman who was friends with Randy until she saw a picture of him and declared him not attractive enough to stay her friend.
Monette MacIntire (formerly Donnelly)
Initially a recurring annoyance, the idiotic Monette would foolishly attempt to become a lesbian, despite her sucking "a whole mess of dick", according to Davan. Eventually, she randomly moved to Texas to hang out with Davan's parents, and ended up getting adopted by them, becoming a family member. She eventually became a real lesbian after hooking up with girlfriend Lisa, and moved to West Hollywood to appear in a bad UPN sitcom.
An antagonistic, whiny nerd, Mike was obsessive and whiny, always insisted on being right, and made "friends" with girls in hopes of seducing them. Basically, he was Randy's version of a lot of needy, misogynistic geeks who chase after women. Eventually he made real efforts to change, found a girl, had a baby... and then broke down again, chasing some friends off. Usually, if the plot requires some regular character to be wrong, it'll be Mike. He's still sometimes sympathetic, but he's usually the universe's Butt Monkey.
Butt Monkey: The strip's biggest recurring example. He gets a lot of beatings.
Character Development: Has gotten much better over the years, to the point where he could currently be considered one of the nicest characters in the strip. Is now a legitimate superhero (of the "real superheroes" variety).
Jerkass Has a Point: One of the major signs of Mike's improvement involved this - Peejee was becoming increasingly angry at work because her boss' new girlfriend was blatantly and unapologetically racist (particularly towards Asians like Peejee). Aubrey called a meeting to reveal a plan to mollify Peejee, and Mike objected due to it not solving the underlying problem. For one, it showed Mike showing genuine concern for another person with no angle towards himself. For another, it showed that everyone else agreed with him, only disagreeing as the distraction was useful as a stopgap measure - they were treating him as an equal and friend.
Nice Guy/Nice Guys Finish Last: Subverted heavily — a major point of Milholland's (and Davan's) is that a lot of supposed "Nice Guys" are actually self-involved, self-pitying jerks like Mike, who are actually quite selfish, and only after most girls because of their looks (something they hypocritically accuse the girls of doing with the "jerks" they go out with). And that said "Nice Guys" often pretend to be girls' friends just to potentially seduce them later, while pining over them like stalkers, none of which is "nice" behavior at all.
However, after his Character Development he now has a girlfriend, a baby, and the respect of his friends (well, as close to respect as Davan, Aubrey, et al can actually express) for his superhero career.
Non-Powered Costumed Hero: He becomes this to an extreme. His daily heroics as Pythagorean include helping people with their groceries, finding lost pets and generally just being a nice guy and he is well loved by the community at large for it.
Oblivious to Love: His total lack of self esteem and inexperience with any kind of flirting, despite being married makes him unable to tell the multiple women (and at least one man) giving him their phone numbers were flirting with him.
Took a Level in Badass: The eventual result of his superhero career, much to everyone's astonishment (particularly his own).
Write Who You Know: Mike is an amalgamation of two people Randy knew — both misogynistic whiny geeks. One person got better from that phase, while another got worse. Luckily for Mike, he seems to be following the example of the one who got better.
Ironically, Jhim, the only recurring gay male character, is the Straight Man of the group, often rejecting the bizarre habits and statements of the others. He tended to get dragged into whatever crazy thing the rest of the gang was doing. He left Boston after a couple years of the strip after several failed relationships (one to a heavily-closeted man with a wife and son), and only returned when Davan left, making him a very rarely-recurring character. He's proven to be a bit of an Ensemble Darkhorse, being one of the most-requested characters for the "Old Familiar Faces" arcs.
Out of Focus: He used to be one of the main cast, and now more than a year often goes by between appearances.
Disability as an Excuse for Jerkassery: As a young boy, he was admitted to a hospital for an ear infection, where he was antagonized at every turn by a boy in a wheelchair. Eventually, Fred and his friends team up to scare him and teach him a lesson... whereupon it is revealed that the boy is in the hospital for a heart condition, and the shock of the scare ends up killing him.
And, not that he feels the need to make excuses, but Fred relishes being diagnosed with Alzheimer's because of the opportunities it allows him to fuck with people.