I have about five stories on the go at the moment, and all of them have their characters. The character who's most like me is 12 year old Polly: like me, she loves to read, is very quiet, likes school, cares a lot about her family, and chews on her plaits when she's nervous. Unlike me, she's one of triplet girls, comes from a very poor broken home, and is eventually taken into care by an older couple. She misses her sisters, though - I haven't worked out if they get back together in the end, or if they stay with their respective foster families.
The favourite of my characters would be Kathleen, from a different story: her parents disappeared one day with her younger brother (who, I learned while writing, is Polly's father) and she ended up in the care of her uncle. He teaches at a boarding school and didn't want a child, so he enrolled her in the school and she's allowed to stay there over the summer. In the present day she's 14, and is known as the 'quiet but sweet' one in her house: nobody knows that the teacher is her uncle, and she hasn't told anyone about her parents and brother.
While I love writing, I'm not very good with plots: I could write for pages about each character and what they're like, but I'm not so sure how they'll react in a certain situation.