User blog comment:Rassilon of Old/Young Justice spoilers at Comic-Con 2012/@comment-800707-20120913022839/@comment-1038387-20120913090931

Power Girl won't work with her Multiverse origin. Unless you give her the identity crisis of the first post-Crisis years. Because Earth-Two didn't exist anymore, her origin had to be rewritten. She became Atlantean, granddaughter of Arion sent into the future to protect her from Garn Daanuth.