There's a third Lightning.
She couldn't remember the events we all saw her involved in, and having met you enough I know you weren't the one dispensing helpful advice and bringing us back together after our group fractured.
You're a person just like us. Comprised of a heart, a body, and a soul. But your heart is gone, isn't it? You've embraced the chaos, just like one without a heart would embrace the darkness.
So what became of your heart? It reaches out to us in the only way it can. It wants to be saved. It tries to control you, to warn us, and when possible... it manifests as Lightning... out of butterflies.
To save Lightning, to save you. We need to steal the heart of Lightning's sister back from Succoth.