Newsarama has the cover to Teen Titans #99, revealing that Bart Allen’s “dark twin” Inertia returns as a member of Superboy-Prime’s new Legion of Doom.
Inertia was created as a clone of Bart Allen and sent back in time to replace him (several issues of Impulse, then the “Mercury Falling” storyline). He later tricked the Rogues into killing Bart shortly after he became The Flash (“Full Throttle”), putting them through hell, and they got back at Inertia by killing him in Final Crisis: Rogues’ Revenge.
No word on whether Inertia is resurrected, brought in from an alternate reality, or a younger version brought “back” through time travel.
I can see Thadd being from a time before his death during Final Crisis or another Earth’s Inertia. it’s not that much of a stretch since Sungirl is an ancestor of Sunboy centuries before the Legion forms.
…
I’ve lost all hope that the writers will try to portray him sympathetically.
*goes back to reading fanfic*
Inertia isn’t a sympathetic character. He made his choice at the end of Mercury Falling and there’s no turning back for him now.