Fic idea for The Flash:
Eobard hates Barry, right? But he doesn't seem to have anything against Iris. So what if Barry died, not for Eobard but because he was killed by another villain, and Eobard tried to go on with his life? Hardly, because he was supposed to be Barry's reverse and without Barry he feels empty, even when he should have been happy that Barry was finally gone.
Eventually, he meets Iris again. But she isn't the Iris he knew. She is depressed- because after Barry's death she felt like she didn't belong in the team, and even when Cisco, Caitlin and Eddie tried to help her she refused (she ocasionally called Joe but grew apart from her team).* And although Iris at first doesn't trust Eobard because he was Barry's enemy, after meeting him again and again without wanting to, she gets attached. Not because she wants to, but because he is the only one that doesn't expect anything from her. He doesn't expect her to heal, or to be strong, or to keep going with her life despite what she lost.
And without them realizing, Eobard also gets attached to Iris, maybe because she is the only one apart from him who knew The Flash in a personal level. And after some time, they start dating. Iris becomes someone important to Eobard, to the point that Eobard decides to rewrite the timeline again to bring back Barry. He doesn't care about Iris forgeting what they had, he just wants to give her back the person she loved. And a part of him also wants to bring Barry back because with Iris he knew a part of Barry that he didn't know when Barry was still alive.
When he travels back in time, he saves Barry because he wants to, not because he expects the team to be grateful. But what he doesn't expect is accidentally meeting Iris again and again, and Iris being the only one of The Flash's team to realize he changed. And what he expects even less is Iris making him and Barry meet again, and Barry also believing he changed.
Eventually they asked him to join Team Flash again -they only decided to do it when they watched Eobard help people without having ulterior motives- and he became a hero too. And when he least expected it, his friendship-bond with Iris and Barry turned into something else. Love.
*Another change in this AU I have to add is that Eddie didn't kill himself to kill Eobard, maybe he tried but survived -so Iris wouldn't hate Eobard for that in this AU; because it didn't happen- or maybe he didn't try to kill himself at all. Also Eddie would be just Iris' friend in this AU since always because in this AU Iris is the one who had a crush on Barry and they started dating some time after Barry woke up from the coma.