He invented the Chronexus (a time window) that she and some of the other Legionnaires viewed various parts of Superman's history (including references to another Legion).Brainiac 5 secretly worked with Sev Tcheru to perfect the Chronexus technology by making it a real, but limited time machine. When this was revealed, Saturn Girl convinced Kara that she should go back to her native era.One Year (and one month) after Infinite Crisis, during World War III, Kara returned, only to find Superboy dead and Superman powerless.Feeling alone and isolated, she became Metropolis' protector along with Booster Gold and Supernova.Soon after, she assumed the identity of Flamebird to fight crime in Kandor with Power Girl as Nightwing.
Kara's self-discovery was interrupted when Lex Luthor used Black Kryptonite to split her into a good Kara and an evil Kara." The two Karas fused back into a single good Kara, who decided her past was not important and acknowledged Batman, Wonder Woman, and Superman as her foster parents.As a result of the Zeta-beam, Kara re-appeared in the 31st century. When Brainiac attacked Krypton, he took Kandor with him, while Kara and her parents remained in Argo. Kara is actually older than Kal-El (Superman); she was a teenager when he was a baby.