She is a member of the Xartans, a race created by the Celestials. As such, she has the ability to shift into any form and replicate any superpower. As the princess of the Xartans, she is betrothed to Karolina Dean in order to forge an alliance between the Xartans and the Majesdanians. This means Xavin is sworn to protect Karolina, which in turns means joining The Runaways in their quest to protect the innocent and defeat the Pride. Xavin is a million years old in Xartan years, which means she's a young adult in Earth years. She is not accustomed to Earth cuisine, but she finds it delicious.
Gizmodo. (December 31 2018)