Okay, so, here's a review of how's this AU story is current going. I'll separate in acts like in the show for a matter of plot idea organization:
Act 1: same as canon, but with that different end; Powder is adopted by Viktor and Vi isn't captured by Marcus.
Act 2: What happened in what would be the timeskip, 10 years passes in this act; Jinx and Viktor creates a new technology in secret called ArcTech(Arcane Technology) while they work in their reputation inside the Academy. Meanwhile, Vi and Ekko found the Firelights Group to resist Silco's increasing influence in Undercity and help those who were still in Vander's side.
Act 3: “Vi’s rescue” like I called. Vi was captured by Silco and he will transform her into a weapon thanks to Singed’s and Renata’s help. The Firelights accept support from the Aquanima (since Jinx was already looking for her sister) to help rescue Vi: while Caitlyn goes with the Firelights to help find where Vi is and to figure what else more Silco is up to, Zeri joins the Academy to gather more engineering knowledge to power up the Firelights' equipment with Jinx's help. The discussion of Hextech weapons and prosthetic body parts starts as some big chemtech machines are starting to show up to cause havoc in Topcity.
Act 4: The Firelights officially team up with the Aquanima Clan(Jinx and Viktor’s clan) while Vi, Ekko and Zeri legaly joins the clan to get benefits around the academy grounds. With the imminent threat of Silco’s power rising, the Hextech’s weapons discussion is heating up, even some prototypes are made. Then, Silco will lead a new Underci- I mean, Zaun’s rebellion at Progress Day.
Added characters from og universe(for now): Renata, Blitzcrank, Zeri, Ziggs, Camille, Zoe, Warwick, Urgot, Twitch. More details about them [here]
That's all for now, I'll work on scenes' connections and polishing.
Reminder that is AU is still a work in progress, stuff is subject to change!