TL;DR LORE AHRI

So, Ahri used to be a fox. Who felt really ~ magical~ sometimes..

She felt like she didn't belong in the fox world. She wanted to become human ! Of course foxes can't magically become human, so it seemed hopeless until one day. She came across athe results of a human battle. It was a very bloody scene, surrounded by dying soldiers. She was drawn to one particular body..

It was a robed man , surrounded by magic, dying, and when ahri got closer to him, his life essence started pouring into her. When it was all over she had found that she had turned into a human, what she had always wanted. But the transformation was incomplete, she wasn't fully human. She adapted herself into human society, and lured guys to steal their life essence. It's probably easy for her, considering she was a hot Asian girl but anyways, soooo she took more lives...

She started to feel ~ regret ~ something she had never felt as a fox. She was gaining human morality, and she didn't know how to stop it. She found the institute of war, while looking for a solution. The league offered her a chance to stay human without hurting anyone if she joined. Ahri agreed and I'm assuming she stopped killing random guys after that.

So yeah, THE END