So we've had the first 8 episodes I think, and the crossover. Boy do I have some crazy ideas now!
But that's for another post. This one's about Nora and the whole situation.
Nora comes back as Barry and Iris' daughter. She helped stop a catastrophe. Making her already seem like a hero to the team. Nora joins the team and bonds mainly with Barry at first. Then after a rough start, bonds with iris. Nora uses a language that won't be affected by any timeline changes, to write in her journal. When she travels back in time with Barry, eobard calls her dawne. Just an Easter egg? I don't think so. A hint to the tornado twins? Maybe.
What if, on the night of the crisis Barry disappears in, iris gives birth to twins. Original timeline Barry and Iris would have called them Don and Dawne. But after the reverse flash forcing Barry to become the flash earlier than his history, and Barry disappearing, iris names the twins, Nora and Bartholomew.
The twins both exibit speed abilities at an early age so iris fits them both with speed dampening kits in a future where cicada is hunting down and killing metahumans. Nora idolizes her father and frequents the flash museum. Learns of her implant, visits the reverse flash at the museum, which let's her know he can traverse time. He teaches her. For a price. Nora travels back, keeping a journal in a time language.
I bet eobard has the exact same journal in his cell and when she writes in the journal, his is updated. He is showing her how to affect the timeline in subtle ways to achieve a complex plan. Much like he did for 15 years while Barry was growing up.
The small changes would also bring a possibility for eobard to be free from prison. Cicada would be caught, because he has appeared earlier and they know his identity. His goal is freedom.
In the future, altered slightly by Nora's trying to change the timeline, iris disables Bartholomew's implant earlier and tells him about his father and sister in the past. Bartholomew learns to use his powers and turns up in the season finale. And there we have Bart Allen. A slightly younger speedster.