Let's talk about Vayne
Vayne has always had that thing of extremism in her lore, or at least the implication of it. She wanted to kill those who used "dark magic" originally, and went to the league in order to find a way to kill the dangerous creatures there. Thing is, dark magic can technically mean someone like Veiger, who's too incompetent to actively endanger people. Also, she would be breaking the rules of the League to kill a champion outside of the Fields of Justice, so she would have broken the law to kill the supernatural and evil characters of the League.
In the new Lore Evelyn (it's implied to be evelyn, but it's not stated) was the thing that tortured her parents and for some reason didn't murder young Vayne. No body believed her that her parents were murdered by a demon (on a side note, what they write it off as?) and so Vayne became determined to kill the Dark creatures and those who used dark magic. Anyway, she got a trainer, Frey, and Vayne learned a lot about dark magic from her. Frey almost became like a second mother to Vayne, but that all ended when during their last hunt together, it turns out she was a werewolf. Vayne killed her, and she went right back to hunting the demons.
Now, I will say that Vayne is not Batman, she never was. However, she does take after him a lot.
> The summoners stared at her uneasily. After all, few potential champions have ever broken into one of the inner sanctums of the Institute of War, startled powerful summoners, and plainly demanded to be allowed into the League of Legends. Fortunately, Vayne's reputation had preceded her, so there was no need for violence. The room in which she sat now was sparse - nothing more than a fireplace with a few chairs. Vayne reflexively adjusted the crossbow on her arm. "When do we begin?" she asked. The summoner who seemed to be in charge of this process turned away from the fire. He was a gracefully aging man, approaching middle-age, with a quiet authority borne of true power. "In moments. First, I want to ask you how you managed to get past our defenses to gain access to the deeper chambers of the Institute." "The same way I know that you are Senior Summoner Ezekiel Montrose and that the woman with you is Summoner Lessa Carin. The same way I know that you take rose-hip tea every day, the route you walk to your home, and that you sleep on a very uncomfortable bed. I am the Night Hunter. Now get on with it. I have already submitted to your authority."
Then there's the whole "my parents are dead." thing, the quest for vengeance against the concept that harmed them. New Vayne certainly shares that, but what's divided the fanbase is the fact that she seems to take in some bizarre pleasure from it. Like, she's not doing this because she sees it as a duty or revenge, she does it cause it's fun. Now, that's something that occasionally comes up with Batman, that he's just doing it because he enjoys it. The thing is that this is not Vayne's character. Just listen to her lines, she's calm, stoic, and doesn't have a sense of humor. This Vayne's lore paints her as a lunatic who likes hurting monsters.
Personally, as long as she doesn't channel Konrad Curze, i'll be fine. I think, and this is just a theory, Evelyn, or dark magic in general, messed up her head.
> Vayne tried to brush the bloody hair out of her mother’s eyes, but that haunting smile lingered in her mind, growing and consuming her. Even as she shakily smoothed her father’s eyelids closed – his mouth still agape, frozen in his last horrific moments of confusion – the demon’s smile seeped through her thoughts. It was a smile that would fill Shauna’s veins with hatred for the rest of her days.
That's all I have to suggest it though. What do you think of the lore changes?