Welp, I read the first chunk so far. On the one hand, Lux and Ezreal are being shipped, which I hate. On the other hand, Ezreal was being an idiot, which pleases me. ASDFAFSDAFSDFHO
(Don't take this as actual criticism or something, I just really hate Ezreal)
I think they're a vaguely interesting couple because of the Piltover/Demacia thing, but they're also a pretty hateable couple. I feel like that's part of the idea: they're the super-photogenic darlings of Valoran. I found the contrast between them convenient to tell the "ghosts of those you've killed" subplot with the Harrowing, and to show the difference between a cocky League superstar who loves to show off on the big stage and someone like Lux, who was smashed into shape by Demacian society and still bears the scars from it.
TBH, the whole plot thread in Factions started because a friend dared me to write a story where Ezreal's dialogue comes almost entirely from Vengeance by the Protomen, and I decided to be cliche about it and have Lux get shot to set him off. (Whatever, she can stand being fridge'd a little.)
One thing I like about Ezreal as a character is that he's such a conceited jerk, but he's also not a bloodthirsty psychopath. He's often way out of his depth without realizing he's way out of his depth, which is very convenient.
I cut a planned "visit to Shon-Xan" scene from the update in part for time, but also in part because it would have meant another Lux/Ezreal scene, and I don't want to derail this into a Lux/Ezreal fic.