Vi is daughter of Victor! This would explain her name and her awesome steam punk look. But who is the mother? Cass! In Cass's lore they explain that she sleeps with important men to learn secrets... Secrets about the glorious revolution i say. This happens while Viktor is still mostly man and Cass has legs (lol). So what does the spy Cass do, she does not want to kill the child but she can not bring it back to Noxus? She names the child Vi and gives the child up to the kind natured Yordles in Piltover. Then the story can pick up from there.
Demaci
Oh and if there was ever a love interest for Vi I'd say renagade Talon would be the best fit. NEVER Jayce.

Let me know what you think, or expand on the idea. I'm not a good writer but if we have any Fan Fiction like this I'd give it a read.

It is settled. LET THE SHIPS SAIL!

So Vi is part human part snake part machine
Seems legit

only if you agree that the shadow isles is secretly Brazil

Piltover is not run by yordles. It's Runeterra's melting pot.

Also, I think Vi should have a hidden passive that makes her attacks against Jayce always strike him in the groin, causing 10 second stuns. If she kills him then she should auto-taunt, "****ING SQUARE!"