Paraphrasing of blurb from the third tankoubon, removing spoilers:

A calm, considerate person who always helped the Princess as the Sol (priest). He has one of the strongest Hearts in all of Cephiro, and used it to support Emeraude's prayers as Pillar and protect her so that nothing got in the way of her prayer.

<Alice> So, Shinji-san, what do you have to say
        about them?
<Satsuki> Not so fast, Alice.
<Asuka> Yeah.  We need to rag on Zagato for a bit.
<ChunHyang> Rag on?  I like him.  And so do a couple
            others.
<Satsuki> I remember one long thread on the (English)
          CLAMP ML about how Zagato was actually good.
<Rei> ... that is only one opinion.  I think
      otherwise.
<Shinji> Can I tell the story behind them yet?
<Satsuki> I guess.  We can talk about him when we
          talk about his brother.
<Rei> That sounds good.
<Yang> Affirmative.
<Shinji> Okay!  Now I can talk!  Woohoo!
<Asuka> What?  BakaShinji, excited!?
<Satsuki> Asuka, it can happen.
<Shinji> So if you want to know what I'm talking
         about, and be spoiled with the RE1 ending,
         highlight the blank space below. It's a tad
         long, though.





<ChunHyang> So what do you want, Shinji?
<Asuka> Yeah, speak up.
<Shinji> Ayanami... can you read the actual blurbs
         from the third tankoubon?
<Rei> Both Emeraude and Zagato?
<Shinji> Yes.
<Rei> Okay.  Do you mind, Satsuki?
<Satsuki> Go ahead.  I'll do the missing line from
          Zagato's, though.
<Rei> Okay. *grin*
* Rei reconnects to BEAST.
<Rei> "She is the Pillar that supported Cephiro
      with the power of her Prayer.  But, she fell
      in love with Zagato and summoned the Magic
      Knights to have them kill her.  She looked like
      a young girl different from her actual age)
      when she was a Pillar;  she looks "grown up"
      now that she has learned of Zagato's death."
* Rei disconnects.
<ChunHyang> Why did we change Zagato's blurb in
            the main character file?
<Satsuki> Because it said: "He loved Emeraude,
          and thus for the sake of his own Heart,
          positioned himself against the Magic
          Knights." and that is a MAJOR spoiler.
<Shinji> Emeraude fell in love with Zagato.  Zagato
         fell in love with Emeraude.  But their love
         was forbidden: Emeraude couldn't think of
         anything other than Cephiro.  She couldn't
         think about him by the laws of Cephiro, but
         she could not stop thinking about him.  So
         she imprisoned herself in the dungeon in
         hopes of forgetting him.  She could not
         forget him, and therefore summoned Hikaru,
         Umi, and Fuu to kill her because Pillars
         couldn't commit suicide -- and at the rate
         she was going, she was going to destroy
         Cephiro by thinking about Zagato.  Zagato,
         on the other hand, decided to fight the
         Magic Knights because he didn't want to
         see his love killed -- even if her being
         alive meant that Cephiro would fall to ruins.
<Asuka> But that's not right!  You can't risk
        millions of innocent lives to be with
        someone you love!
<Alice> But that is an idealistic love, a love that
        people would dream of... that someone cares
        about you so much that they would risk the
        well-being of a whole world for you.
<Asuka> I guess.
<Rei> So the question boils down to "Do the ends
      justify the means?" .....
<Satsuki> Send us mail with your opinions on
          Zagato.
<Alice> I hope we don't have polls on every
        character file page.
<ChunHyang> Our 28.8 won't be able to handle it! 
<Yang> Oh, and Satsuki-san?  Can we get a visual?
<Satsuki> Emeraude after Zagato's death, the image
          next to the blurb in the third tankoubon?
<Yang> Yes.
<Satsuki> No problem.  BEAST! 
* BEAST whirrs.
<Satsuki> Here.  One adult Emeraude.
<Alice> Much different from the young girl that we
        usually see.
<Asuka> Now THAT is the voluptuous,
        tempting twentysomething woman I want to be!
<ChunHyang> Does "love makes a woman beautiful" fit
            here?
<Yang> Emeraude is beautiful in either form...
<ChunHyang> *giggle* True!