Arashi feels it necessary to change sides the very morning after she finally sleeps with Sorata, presumably in an effort to keep him from dying for her sake

I'm only being picky about this because Arashi and Sorata are the only reason I read and love X, but that's only in the anime version. Not that her situation in the manga is likely to wind up any better, given what CLAMP showed before putting the series on hold. -_-