Tainted Love I - Alexiel
Everyone loves Rociel.
Everyone is blinded by his radiant, unnatural beauty. That is, until later on, when those around him are exposed to his insanity and cruelty. Of course, they still follow him, but that's because he's become a tyrant and they fear him.

When Rociel first told the young Katan about his twin sister, he said that she hated him.
Of course, she didn't, she loved him in a condescending, older sister kind of way. So much so that she failed him by not killing him when she had the chance. It wasn't an attempt to hurt him, (as he believed in his paranoia), she just couldn't bring herself to do it.

Common opinion among TK readers would seem to have it that his longing for his sister is of a similar nature to that of Setsuna's for Sara. That he wanted a sexual relationship with her. I suppose this would make sense, she is after all, his only equal in the whole of creation. He believes that they ought to be together, because they are the same, that only they can love each other. Presumably, their long separation only served to increase his desire for his twin.
TK is a very confusing story, personally, I'm not convinced there was any twincestuous element there. And wouldnt they make a strange couple? Alexiel with her dominant, warrior-heretic ways and Rociel being such a submissive girly boy? I'm not saying it wasnt like that, but when I read TK, I never got any idea that Rociel fancied his sister. He loved her, he wanted her back, but as twin sister, not a lover.

She is the stronger, more sucessful of the two. While he was working under the creator's command she went off and did her own thing and started a revolution. He cannot compare himself favourably to her achievements (we mustn't forget the shades of sibling-rivalry). Even though she was persecuted by Rociel's beloved father, the creator, she came back strong. He does the opposite and deteriorates despite an ostensibly more privilaged life.