Petara is one of the Martian colonists who crash-landed on Earth some 250 million years ago. Caustic and snarky, Petara was declared an apostate and a heretic by the White City for her athiesm. And yet, for reasons unknown to the others, she was not executed like other apostates.
An outcast among the other (faithful) colonists, Petara doesn't win herself any friends by often playing devil's advocate and raising arguments for the sake of doing so. She's openly hostile to Ress, but appreciates her guile; Ress will sometimes share elements of her various schemes with Petara, content that the outcast's warnings will fall on deaf ears.
Petara is not a warrior, and seldom contributes to physical work-- increasing the ire the others feel towards her. Like Kellin and the nameless one, she has a desire to preserve the history and culture of Mars that the others find so useless.
The name Petara is an ancient Martian word of passionate negation.
At the time of the landing, Petara's age is unknown-- but she is both the bitterest and the oldest of the colonists, probably 18-20 in Martian years (approaching 40 in our years).