Bart could see the jealousy seep out of Wally's pores. It was obvious if you knew where to look for it. Thing is, there was so many other important things to worry about that Bart was sure no one else bothered to pay the red head much attention.
This was great for Bart though, because it made every smart remark, every jab at Wally's speed, and every put down hurt that much more. Wally's speed was always a mental thing; he blocked himself when he was sad or depressed. Hopefully Bart could render Wally completely normal soon. Hopefully Bart could save him.
His grandfather was supposed to die that day. He was supposed to die and leave a widow pregnant with twins. Die and leave Wally with a legacy. At first Wally wouldn't be able to handle it, he'd mess up and fall down a lot. But then Wally would take it and run with it only the way a speedster could run. Nearly every trick the speedsters of his era knew could be traced back to Wally.
Wally West knew speed, he was built to be the Flash. He was built to run. And one day he ran and ran, and ran straight into the speed force. He stopped the bad guy, but the best speedster Bart had ever seen was gone. And that was the beginning of the end.
Saving his grandfather was supposed to negate all of the bad things that would happen. Barry lived and Wally never becomes Flash, Wally never becomes Flash and that future that Bart used to know would never happen. Barry would save lives for another ten years at most and then retire, Wally would be completely normal by then and unable to take up the mantle. Hopefully Barry keeping the mantle would be all the world needed to have a better future.
Bart wouldn't grow up not knowing his grandfather. Bart wouldn't face a desolate future with a dark sky and no people. The world would be saved.
But Bart would always feel his heart race every time Wally ran. He'd always see the dark red of the suit disappearing as the smell of ozone filled his nostrils. After all, he never really knew his granddad, but he grew up on stories of Wally. Don and Dawn trained under him, and Bart watched him disappear.
Wally was his hero.
And if he had to break his hero, no he wasn't breaking his hero he was killing him, if he had to kill his hero he'd do it. He'd do it for the world.