Gray was Kenny Paynes sister. Kenny and her were both new in the valley and to that stress already Kenny got bullied by a dude name Anthony LaRusso so he went to take Karate classes at a dojo called Cobra Kai

TIMESKIP

Kenny became stronger and began bullying Anthony LaRusso as revenge, Gray knew but she actually didn't really care, she thought he deserved it. Gray, Kenny and some other Cobra Kai students were at the waterpark when Kenny saw Anthony and started bullying him calling him "LaPusso" and then he put four floaties on him before pushing him into the pool