The Story of Vi
Vi grew up on Zaun's streets, in the undercity's scrape-and-survive culture where you learned to fight or you didn't learn much else. She was good at it — brilliant at it, actually — and led a crew of Undercity kids who were doing what undercity kids do: surviving creatively, pushing back against whoever was pushing down on them. That life ended badly, in the way that Undercity lives tend to end badly, through a catastrophe that cost her the person who mattered most.
She eventually made it to Piltover as an enforcer — a law enforcement officer working for the city-state she grew up beneath. This is, from a Zaunite perspective, a deeply complicated choice. She hasn't become what Piltover represents; she's using the access it provides to do what she'd be doing anyway, just with a badge and hextech gauntlets that can punch through walls. Her relationship with Caitlyn, her partner, is the most stable thing in her life.
The complication that doesn't go away is Jinx — who used to be Powder, who used to be her sister, before the catastrophe and Silco and everything that followed. Vi's love for Powder and her relationship to who Jinx is now occupy the same space in her, and she hasn't found a way to reconcile them. She goes looking anyway, every time the opportunity presents itself, because she can't not look. She's not sure what she'd do if she found her.