Kai'Sa VS Eveylnn VS Elise VO's

If you were to not read any of the lore, the VO's of the champions as well as their look and playstyle would determine a lot of what you need to know about who they are and what they're identity is. Eve has a strictly distinct personality from Elise just based in quotes alone. They're both attractive, they're both mass murders, they're both charming and seductive, but in terms of just raw quotes Eveylnn conveys a certain measure of brutality with her VO, i.e. "The height of their happiness, is the depth of their pain."

Queue that together with her other voice lines where she talks about how she feels and hungers, and you get the idea that Eve is doing this because she's addicted, she craves pain and suffering and torment, it makes her who she is. Elise on the other hand, never really directly states what she wants, much of it is a mystery, all her quotes are about sacrifice and growth, guidance and divinity, generally positive things that mask her truly horrifying nature, and what she does to others in order to keep herself alive.

How does this relate to Kai'Sa?

For Malz and Kass , their voice lines have a kind of overarching effect over them. Malz's voice is kind of rippling and crackling, and Kass's VO is much the same, but a touch muffled.

For example, her counting quotes. She's literally counting up her kills, the number of people she's destroyed. What would give this some more pop is if there was a static-effect around the quotes as they get higher and higher in count. Much like how you can hear Malz's voice crackling and warping when he speaks, or how Kassasdin is talking through his mask, the tuned effect of the lines could bear more witness to the fact that Kai'Sa is not just a lady in a suit.

She's wearing the suit, but the suit is also wearing her.

She starts off at one, as she gets to ten-ish you'll hear a bit more distortion in her voice, fifteen-ish its warping, doesn't sound quite right anymore, the higher it gets, the worse it gets. The Symbiot part of her knows it's winning, and its excited. But on the final line, when she says "I'm done counting." It could be rephrased so that she expresses that "I'm done counting" in her normal flat VO, accentuating the fact that they may be together, but she's the one in control.

She survived the void because of the suit, the suit survives in the void because she allowed it to bind to her. The relationship is symbiotic, but other wordly in its nature. This isn't like those spiders that keep pet frogs to protect their eggs, this thing is literally on her and in her. [( ͡° ͜ʖ ͡°)]

Her VO needs to reflect that, otherwise...yeah, she's just gonna feel generic and flat. The suit allows her to cling to the one thing that's kept her going all this time, hope. Anytime she monologues her bullshit about that, she should sound like herself, even if it is boring, that just might be who she is. But when she's going for kills, hitting her skillshots, giving off those short sweet quotes about how she's about to wreck the fuck outta something, that needs to have a 'predator-esqe' feel, and giving her that rippling crackling void-over on her lines might be a little better than just her alone.