Adonae — David Gordon

Sami has helped her alien friend, Brian, and her human nemesis, Alejandro, to escape Earth. But she is not someone who likes to be left behind. Soon she, too, is on Adonae, a world of oceans and volcanic islands, and of staggering technological marvels.
Sami soon discovers that on Adonae she and Alejandro are the aliens. Oh, and the planet also has a real problem with pirates. But the greatest danger to Sami and Alejandro is KetaNim, the ruthless ambassador of another alien race, the TakTi. He claims that the kids from Earth are dangerous and must be executed.
While the ambassador conspires to take their heads, Sami and Alejandro get busy learning from the Adonae. Sami becomes a “scombro,” a reader of people; Alejandro a “quick eye,” a martial artist of the rope.
They will need their new skills and growing friendship to keep KetaNim, and his vicious assistant, KetaGar, and the Adonae pirates from having their heads after all.