Poor Pii...
For Heronia, Pii was just a pet bird, she compared to Bertia doesn't know she could communicate or bird shift form to a human, didn't knew that it's power could "drug" people around as both of them probably didn't read the manual of the game.
For Pii, it acted to protect it's master and her wish, but as it's still pretty young and recently just got bit stronger, couldn't overpower Kuro, committing suicide in last effort to help her friend...
Guess Heronia is now on her own, she was only following the game story to the bone not realising it's a real world, she was severely misinformed and shouldn't be punished harshly...
Thanks for the scanlation!