Well this is in the same continuity as the diniverse Justice League cartoon (I assume) so Brainiac has already invaded Apokalips before in this continuity.
Short version is that Starro was one of the creatures the Collector had captured that Superman inherited when he and Lobo defeated him. One day it attached itself to Supes, and its implied it had been controlling him for years.
Cut to Batman Beyond times, When Superman invites Terry to join the JLU, during a time when someone is attempting to kill off members, Cue Terry stumbling on Superman's possession and the fact he has been breeding dozens of Starro's to possess everyone on Earth.
Cue fight between Batman and mind controlled Justice League, when its all done and everyone is freed, Aquagirl discovers their origin with telepathy, and Barda uses a boom tube to send them back to their home planet.
no subject
no subject
no subject
Short version is that Starro was one of the creatures the Collector had captured that Superman inherited when he and Lobo defeated him. One day it attached itself to Supes, and its implied it had been controlling him for years.
Cut to Batman Beyond times, When Superman invites Terry to join the JLU, during a time when someone is attempting to kill off members, Cue Terry stumbling on Superman's possession and the fact he has been breeding dozens of Starro's to possess everyone on Earth.
Cue fight between Batman and mind controlled Justice League, when its all done and everyone is freed, Aquagirl discovers their origin with telepathy, and Barda uses a boom tube to send them back to their home planet.