We might have been wrong all along about Jinx's sister...
As much as I love the "human experiment subjects at child age" narrative with Vi and Jinx to explain their connection, Vi's amnesia, and their semi-superhuman skills. (Not magic, think more of Captn America level of superhuman), there is a new potential theory to consider.
There was one line in Jinx's Bio that struck me: some claiming that she was a spirit of some sorts, a chaotic retribution of those that died during the incident of the creation of the great canal in Zaun. Blind rage, a thrist for revenge, and madness, all mixed with the good old zaunite optimism and anarchism (two things that go very hand in hand down there). Although that makes for a perfect dramatic explanation, the truth could be simpler: Zaun is literally the most civiliced yet most anarchic place in all of Runeterra - while at the same time filled with negative energies about those who have it better. Jinx, in this theory, is more zaunite than every zaunite is in that regard: anarchy with a distate for piltover's system, culture, aestehtic, and generally everything.
And if she was a spirit, she'd also have a sister-in-kind that was the total opposite of her: Janna, who just wants to help people - literally the most crazy thing Jinx, who only sees people at objects that move hilariously when scared or pranked, could ever imagine. What is a life without blowing stuff up? Can you even imagine that? Total madness, am I rite?
Also, she CARES about people seeing her doing her stuff. While, of course, she could just do it for the fame, isn't this the same Janna needs for maintaining her power?
Sure, first of all the comparision seems silly, one a goddess with magic powers, the other "just" being a semi-superhuman. But one is fueled by wished and prayers actually directed to her, the other is an expression of the underlying atmosphere of Zaun. None prays to Jinx. None uses her name to insult someone or wish them bad luck (or maybe they do? Gives "putting a jinx on someone" a whole new meaning...). None officially respects her. And no one sees her as a higher being, just as a really peristent and creative punk. Maybe the copycats inspired by her could be seen as a group of "believers", who knows?
As for her obsession with Vi: Vi is what Batman is like for the Joker = the walking embodiment of someone who could take fate and the world into his own hands, but abides to the system and enforces the rules of it. A Zaunite fighting FOR the system? TOTALLY ABSURD! For Jinx, who in the theory is the embodiment of Zaunite anarchy, this would instantly make her her arch-enemy, especially since she doesn't want to kill her, but rather join her, just how the Joker doesn't want to kill Batman, but to break his iron No-Killing rule (even if it would mean the Joker's death). To make it short: Jinx wants to befriend her, but in the "come back to the dark side where it's awesome anarchy" sort of way.
Also, even if this was true, we would have no clue if Jinx herself was even aware of it. Imagine you were a god and didn't know because you were too busy doing random shit and lacked self-reflection. She instinctively seeks fame and attention because it keeps her alive, but with no real idea WHY she does it apart from "it's fun". And even if she would know Janna as "her sister", that doesn't mean she fully understands what she or Janna even truly is. Remember, we as readers versed in fantasy literature know of such systems and functions of magic, but a zaunite street brat? No chance.
And the first thing I thought about this: if this is true then we will get a Shen/Jinx story at some point. Imagine if he cuts her with his human-sword and it has no effect and they both are like "Wut?! O_o"
Anyways, I usually like the Jinx and Vi sister theory more, but this is also legit that you have to consider it.