No, no, nothing like that. It's a bit of a spoiler, so if you haven't read or seen it, please do not read what comes now.
Freya fell in love with her 'papa', the husband of Hibiya-san, the people who created her and Chii. Because of the pain it caused her she wanted to stop existing, but Chii urged her to move her 'spirit' inside of Chii's body. So basically it was both Freya and Chii living in the same body. Nothing evil, just her sis.
12-Feb-2005