DbD is still fairly new, even to me. Hell, even though I've been kicking around some parts of the story for years, the major plot points were written over a weekend. So I'm still working out some of this stuff, so take that as you will.
Chelle
Name: Michelle "Chelle" Leferve
Age: 28
Occupation: "Hurting people and breaking things for money."
Chelle a spellcaster, quite a good one in fact, who makes a living by renting her services out. While this sometimes takes the form of causing destruction and mayhem, it's more often something less exciting, like defeating security, bodyguarding, or identifying some artifact or magical oddity. She prefers these jobs, as they're more conducive to dying of old age.
Chelle has a reputation for being an incredible martial artist, a spellcaster of nearly godlike power, and being essentially impossible to kill. While none of these are even remotely true, she takes pains to complete her jobs in ways which encourage these rumors. Because of her persistent campaign of disinformation, there are only a handful of people who claim to have accurate information about her whose information is, in fact, accurate.
Useless trivia: Chelle is named for the Beatles song, and her nickname is borrowed from the protagonist of Portal. Chelle is loosely based off Morgin from Brimstone Zero.
Andrea
Name: Andrea McKenna
Age: 19
Occupation: Student
Andrea is Chelle's apprentice, which basically means that deep down, Andrea is probably a masochist. She's barely out of high school and hasn't even held a job yet, so she's something of a blank slate. While she's fairly naive, a chance encounter with a moon landing conspiracy theorist has left her incredibly skeptical to new information. (Listening to someone who failed high school physics talk about flags and dark skies often has this effect.)
While Andrea's still not very good at spellcasting, she seems to have a talent for it, learning the basics and completing her first cast after three months of study, something that usually takes six to twelve months to do. (Spellcasting is easy. Learning to do it is incredibly hard.) Unfortunately, her hands-on experience is fairly limited, as Chelle's job is too dangerous for her to watch, and she doesn't have the stomach to watch Anya's.
Useless trivia: Andrea's name is borrowed from a character in Brimzero, but otherwise she's the only main character created specifically for DbD. Well, except for one who isn't going to show up for a looooong time, and he doesn't count anyway.
Anya
Name: Anya McKenna
Age: 26
Occupation: Healer
Anya is Andrea's older sister, Chelle's girlfriend, and technically their landlord. While she hasn't been studying spellcasting as long as Chelle has, she specializes almost entirely in healing, something Chelle can't really get the hang of. She's a bit of a hardass, but she's a hardass with a heart of gold. Or something.
Useless trvia: Anya doesn't appear much in the first book of DbD, so she's probably the least well developed of the three. She's very loosely based on Tracy from Brimzero.