Regeena Peterson is a new character introduced in Mission: Earth, who quickly befriends Betty and Noah. She is the daughter of Principal Peterson, and, as far as he's concered, she's a sweet, demure, respectable girl. But as soon as she turns his back, her real personality comes out, which is quite the opposite. Betty finds Reegena refreshing, and around Regeena she comes out of her shell. In fact, Betty becomes a bit of a project for Reegena; she is determined to make Betty get out and "do stuff!". She has a somewhat bulkier build than most of her classmates, but given her father's athletic interests and build it's quite likely that this is muscle as opposed to fat.
Regeena has a distaste for Penelope, after Penelope's attempts to woo her upon hearing that she is Principal Peterson's daughter (wanting Regeena to be her friend only to raise Penelope's own social status). In "Girl Power", she unknowingly befriends Sparky (who had been accidentally transformed into a girl by a magic crystal). She and the female Sparky become good friends during the episode. When he is returned to normal he passes himself off to Regeena as the brother of his female identity. In later episodes, Regeena is often suspicious of Betty, Noah, or Sparky when they unexpectedly leave for missions, though she often takes their disappearances in stride.
In "The Future is Now", Reegena is among the Galactic Guardians of 2013.