>>713091248
>>713091248
If you kill Irina yourself (e.g. for her maiden blood), Hyetta will never appear. Likewise, if you never met Irina, Hyetta won't appear either.

The game never elaborates on this, but either Irina fakes her own death after giving you the letter (and that's why killing her yourself breaks the quest), or Shabriri possesses her, we'll never know for sure.