Yan Lo is the main villain in "Wendy Wu: Homecoming Warrior". He comes back every ninety years to take over the world, if he would not be defeated darkness would take over the world. In the movie "Wendy Wu: Homecoming Warrior" he possessed the bodies of people to drain Wendy's powers, the powers she got from the the Yin Warrior. The Yin warrior would be her great-grandmother and she was reincarnated as Wendy to defeat the evil Yan lo. At the end of the movie Wendy fights Jessica, possessed by Yan Lo. She made an true sacrifice to save Shen, the monk who was send to inform Wendy and teach her Kung fu to defeat Yan Lo. When Wendy made that true sacrifice and finally defeated Yan Lo he would never come back, because he was defeated forever.
This is Jessica, the person Yan Lo takes over to try to stop the Yin Warrior.