Well, since I just wrote this WHOLE big thing for the duellists mailing list about why I support Shiori and I certainly don't feel like typing it again, I will just cut and paste ^_^
Shiori, despite being a truly manipulative individual, really doesn't want to be a martyr. I can imagine (and I assume from context of the show) that she has spent her whole life in a state of self-loathing. The poor woman has NO self esteem! Now, Shiori doesn't let people take advantage of her on purpose like some people who have no self esteem, because I think that that is what she fears most. She has dedicated her life to making something of herself...but not in the way most people do. She doesn't want to make HERSELF better...or even the world. She wants other people to see HER as perfect and grand and wonderful. Shiori just wants to be perfect. She wants to be everyone's everything. And that is because she can find no value in herself. She doesn't get any kind of happiness from feeling good about herself internally...she is only truly happy from external praise. Some people can say to themselves "I did a good job today" and they are happy. Not Shiori. Someone has to say "Shiori, you are looking lovely today, and might I add that you did a very good job." And THEN she is appeased. But only for a little while. It's an endless loop that she has found herself in. It's also why she will do anything to be the best. To be perfect. She doesn't care who she hurts...that is why most people hate her. Fans of Juri or Utena or Ruka or anyone who Shiori has had contact with say they can't stand her because of who she's hurt or what she's done. Although, in the case of Ruka, she was only trying to manipulate him so she could be dating the new man everyone at the school wanted. Another cry for attention. If she had him, and everyone else wanted him, she would be the best. She would win. She just didn't realize that she would actually have feelings for him, and that he would destroy her by causing her worst fear...he took advantage of her. And she fell for it. And it's no wonder she locked herself away in her room for a long time.
OK, my train of thought just kinda jumped the track, so I'll talk about Juri for a little bit. OK, now as we all know, Juri truly loves Shiori. Personally, I don't consider Juri a lesbian because she has never shown interest in being attracted to or having feelings for any other women. Just Shiori. That time she started coming on to Utena to get her ring from her doesn't count because it was a ruse. I would say a lesbian would be a woman who is capable of being attracted to and having feelings for women like a straight woman could for different men. Because a lesbian woman chooses women over men because of the way she FEELS. Juri, though, doesn't really seem to care. She JUST loves Shiori. I don't know if I'm making any sense here, but I think Juri's feelings for Shiori shouldn't be pegged as just "Oh, she's a lesbian because she likes that one girl." It should be considered what it it. Love. Juri picked a person. Just a person. Gender has no meaning when love is real. *a-hem* But that's a different discussion altogether ^_^ Anyway, Shiori was always best friends with Juri because Juri seemed to have it all. And having it all is what Shiori wanted. And she would do anything to have it. So she put on her innocent face for possibly YEARS (I don't know how long they were friends) until the time was right to take that boy from Juri. Poor Shiori thought that taking the boy would prove that she was better than Juri because the boy picked her OVER Juri. Unfortunately, she didn't realize until the Mikage seminar that she had always been the most important thing to Juri. But, once again, Shiori twisted everything around so that she would once again come out as the winner. She said to herself "Juri loves me! And since I don't love her back, I will always be one step above her!" She finally felt so grand and wonderful because she knew if she kept herself away, Juri couldn't possibly be happy. Then, of course, she freaked out because her brain suddenly went "Crap! Juri loves me! That's kinda gross!" Now, I don't advocate the fact that Shiori would use something like love to get her way. And I don't appreciate the fact that she used her secret knowledge to seduce Juri to get the sword from her...AND I don't support that Shiori thought it was so disgusting for Juri to love her...so disgusting, in fact, that she became very angry. But, honestly, I think a lot of that was the forces at work from Mikage. Because after it was all over, Shiori seemed to suddenly have a new fetish for Juri. So, I forgive her for being brainwashed in an elevator. That isn't her fault.
Anyway, I guess what I'm trying to say is the main reason I support and like Shiori is because I feel sorry for her because she tries so hard to be so much to so many people. Date the popular boy, be the friendly girl, have someone as powerful as Juri in love with her, etc...that she will never truly be happy. Because the way she gets her happiness is so fickle. It never really sticks. The boy can dump her, her friends can leave her, and Juri may, someday, move on. But then what will she be? She won't even really have a reason to do ANYTHING if there's no one to tell her what she's doing is good. This is why I wish she would stop trying to be so all-powerful and actually be with Juri. Or at least be friends with her. Because, lord knows, what Shiori really needs is someone who cares.
If you wonder how I seem to know all this pedantic internal psychobabble, it's because, honestly, I am a lot like Shiori. So I understand where she's coming from. But I don't hurt people to get my attention or my compliments or my love. Although I am a bit of a ham...and I like the spotllight...I don't want any enemies. And I don't want to be mean. So I don't use people and no one gets hurt. Shiori doesn't even care if she has enemies...because even if they hate her, at least that means they're thinking about her.