OK…the Flash, one of the few that it hasn’t been done with that I can see it working…
Wally’s family life is finally settling down. He’s found a paying job. Jai and Iris’s ageing seems to have stabilized. He and Linda are even able to manage some alone time.
It’s good.
But everything breaks down. Zoom, Chronos, or some other time-based villain attacks.
Wally wins the day, of course, with the twins’ help.
But it’s not a victory without price. The temporal energies involved in the fight kick-start the twins ageing again. Wally, Linda, the JLA, the JSA, the Titans, and so forth do what they can - pooling their own scientific knowledge, calling in favours, etc.
But, in the end, it’s to no avail. The twins die of old age before their 5th birthday.
Wally and Linda are driven to despair, and they can’t even turn to each other for comfort, because they both blame themselves, and each other, because they allowed the kids to play hero with Wally. Their marriage is in shambles, even if they don’t officially break.
It begins to effect Wally’s job performance, and he’s fired.
His children dead, his marriage a wreck, his job lost…Wally’s desperate. The other heroes can’t help him - he’s fallen into such a black hole, their support rings hollow to him, and all they can do is support him. They can’t change the past.
Everything Zoom’s said to him comes rushing back. It’s not that they can’t change the past, it’s that they won’t. They say they shouldn’t…Wally even believed it himself, even after Zoom killed his kids the first time. But, he brought them back, didn’t he? And that didn’t hurt things. Granted it was an accident, but the principle holds, right?
So, he breaks the rules. He steals some of Chronos’ tech, and prevents the kids’ deaths. And things look fine.
So…why shouldn’t he fix more things? Why shouldn’t he break the rules?
He helps prevent the decline of Hunter Zolomon’s life, preventing the creation of Zoom. The changes are bigger - the twins are still infants, for instance - but, hey, even better.
So, he continues making changes, trying to fix everything he thought went wrong.
Barry didn’t need to die.
Neither did Ted Kord. Oh, but that turns the world into Max Lord’s personal playground. Well, we’ll just kill Max a little bit early, then. Maybe screw up his attempt to remove the Lord Havok technology.
There. No more Max, no more OMACs.
But, why stop at Max? Why should Lex Luthor not have a convenient accident before coming to Metropolis?
Why should the Joker have walked away from the accident with the chemicals?
Why should Hitler have not died in the trenches in WWI? Why should Josef Stalin have made it to adulthood?
Why shouldn’t he just remake the world to his liking?