I actually want to get this off my chest here. I have a back story for Light and Stephanie.
Light has known Steph since she was born coz their parents were good friends. When she was seven, they lost contact with each other after she killed her parents and ran away. But even after they lost touch, she's been watching him grow up, kind of like a guardian angel but as a demon. Later on, they meet again after Light becomes Kira. The only way he recognizes her is her demon eye that is always covered up with her bangs. Light gains a love interest in her and becomes a Yandere. He even gets jealous when she loves a cat more than him, which is most likely false.
Done!! XS