Anon asked: How would Zucest play out in a time where Ursa didn't just gank Azulon and wander off, but killed Ozai too (because he obviously can't be trusted)?
First of all, Zuko would need some therapy… but not as much as he did on the original version of the story. Azula would be conflicted because she's pissed that their mother killed Ozai, but she's also surprised that Ursa had the guts and was smart enough to do it.
The main thing would be that, without Ozai, the main source of problems for their family, especially for Zuko and Azula's relationship, would be gone. It would allow for their dysfunctional family to heal almost completely (Ursa would still make some mistakes but things would be easier without Ozai encouraging and rewarding bad behavior).
Having a mostly normal home, would make Zuko adn Azula become close friends again. And I can picture that, in the beginning, while she's still grieving her father's death and is still resenting her mother, Azula would be very lonely and vulnerable, and only trust Zuko to help her. I can see her sneaking into his room at night and staying with him until morning because she either can't sleep or is having bad dreams. Zuko's genuine love would make her much happier than Ozai's conditional affection ever did, which would pave the way for her to become much more well adjusted… and for her to develop romantic feelings for her brother.
And, of course, the feeling would be mutual. Zuko was suddenly free of his abusive dad AND finally got his little sister's affection. That would be paradise for him, and he would want to hold on to it, which would make him very protective of Azula, which she would reward with more love. Once puberty hits, he will be forced to acknowledge that he loves her as much, much more than a brother is supposed to love his sister.
All it would take is one cold winter night, with these two snuggling in bed and Azula will go "screw it" and kiss her precious Zuzu, who just wouldn't be able to resist anymore.