I, for one, would like to see how you'd make Emily into a chatacter both in canon and in Mirrorwatch, both in terms of lore for why she's fighting and her abilities.
In regards to canon I would keep her as a civilian, in the data logs it's very obvious that her character was being set up to be a window into civilian life during the invasion, which is good because we need that connection to the publics reactions. How human and Omnic relations are affected by the Invasion. There is also the obvious of making her and Moira related, add some complexity and knowledge to her character that not a lot of the characters wouldn't have. I would mainly characterize this as a dislike of her aunt but having more complicated feelings about the situation, possibly even make her entire family situation complicated? It would kinda explain her lack of connection outside of Tracer. Speaking of which, I would also have her have connections to other OW members that are not reliant on her being Lena's girlfriend (like her and Genji being friends cause I find their dynamic cute).
Another thing I would do is make her a very artsy person, not only because it opens the door to her character outside of Tracer, but it furthers the parallels between her and Amelie. Speaking of which, I would have history repeat itself here, I would have Emily be kidnapped by Talon at some point, I would have her put up a pretty good fight, and I would have her be rescued before Talon could even try to brainwash her, mainly because Widow wouldn't want someone else to go through that pain.
Also she's an absolute dork and is in a bunch of fandom spaces.
As for MW!Emily I'd keep all of what I just wrote the same, only changing when the accident with Lena happens. After Lena disappears and then reappears as a Talon agent, Emily is devastated. She's also angry, angry that Overwatch didn't try more, angry that they aren't even trying to help her now even though what's happening is their fault. So she steals some Overwatch tech, mainly some of her Aunt Moira's tech. She then goes on the hunt, both for Lena herself and a way to fully help her with her chronal dissociation. I like to think she's more of a neutral force.
Not on Talon or Overwatch's side, sometimes her motivations align more with one side or the other but she's usually on her own. Though as a future plot point I could see her being directed to MW!Junkertown by either MW!Sombra or MW!Cassidy, where she meets MW!Winston and finally gets not only the chronal accelerator (my hc is that MW!Tracer is using a modified chronal anchor, which was a prototype of the chronal accelerator in canon, which also makes MW!Lena's state a lot more unstable) but also that separate chronal accelerator that allows Lena to remain in the present with her being physically separate from her accelerator.
