There is some weird variability here because I too pushed her to the dark three times and no matter what I said to her at the Pillar I could not stop her from eating the souls and becoming Dark Xoti!

If you pushed her to the dark then it's normal she became Dark Xoti...

If she became Dark Xoti after pushing her to the light or stopping her from gathering souls then it would mean something...

It almost feels like there are two relationships going on during this.  Her relationship with the character, and her relationship with her God.  Depending on how she feels about you, she might decide to ignore what you're trying to get her to do.

 

Anyone ever try to keep her from gathering Souls at all?  I'd guess the quest just sits in your log, unprogressed, with her not freaking out.

Does dark Xoti have any special powers?