Faafa is Ren sister even thou they are sharing the same body.

Faafa maintains a happy, cheerful attitude wherever she goes. She is also quick to become attatched to those who show her kindness, as shown with Ai. She is also a bit emotionally unstable at times. Faafa doesn't at all mind abusing her powers to get what she wants. In contrast to his sister, Ren is brash, rude, and somewhat of a punk. He enjoys picking fights with others, regardless of their status. However, he has great respect for Zero, and eventually comes to like Ai. He's also driven to ptotect Aura users from attack by human extremists. Like Faafa, he also doesn't at all mind using his powers whenever he likes.