Misty is styled after the character of the same name from the Pokemon anime and is Mystic brother.
Misty is portrayed as the average little sister, annoying Mystic. Misty is mostly the opposite of Mystic, being loud and patient. She, however, considers herself a social outcast, rarely speaking to anybody she doesn't know.
For more info see Lord Anti-Misty.
Lord Anti-Misty is Misty's evil counterpart a ruler of Anti-Fariy World. She was created when Misty was zapped with the Evil MakerMatic 21.
Misty made a small cameo apperance in Fairly OddJonas, the one who told the Turner's to skip the concert. During that time, she didn't like Timmy.