In case some people haven't picked up on the cause for the hostility between PSI and Kevin Poe, leader of the New Purple Gang: Kevin's father, Dr. Sebastian Poe, founded PSI in 1986, after discovering what he calls the "Psi Serum," capable of stimulating even the slightest genetic potential for psionic powers in a human being. He used it to create supervillains for PSI, which made it a major player in the criminal underworld. Dr. Poe was later betrayed to law enforcement by his second wife, Madeline (now the PSI supervillain Medusa), and her lover Psimon, who took over the organization. Kevin wants revenge against Psimon and Medusa, and to take over PSI as his birthright.
According to the write-up for PSI in Champions Villains Vol. 2, p. 143, in 1995 Dr. Poe was sentenced to twenty years in Stronghold. He wasn't part of the 2009 breakout, so is still there; but obviously, his sentence will be finished next year.
Sebastian Poe's release, and reunion with his son, could be the impetus for a significant story arc bringing the conflict between PSI and the New Purple Gang to a head, with our PCs caught between them.