Most people regard vengeance as a dish best tasted cold... not Poprock, born of an angry young girl burning to avenge her father's murder. Her main power is the ability to unleash the energy contained in items when she throws them - she carries a whole bunch of ballbearings for the purpose - backed up with an extreme talent at the martial art of capoiera. Her general athleticism also makes her good at parkour. Quite a heady mix for a budding super-powered character!
The backstory gives involvement with known supervillains, who helped her identify and harness her powers, but given other associates she could as easily be a superhero instead. As a teenager, she'd also fit well into any game involving young superpowered individuals.
This is a well-constructed character with plenty of potential however you decide to use her.