Some people seem to not read the story at all... c'mon...
Pii was described by Zeno as very young spirit, just recently after graduation gaining some power, as he was with Heronia he was linking with her telepathically just like him and Kuro is. Kuro doesn't speak human either, she is technically a young teen and acts accordingly as Bertia.
Pii had some knowledge of Heronia, everything from the game, but due to changes of Bertia did and no knowledge of Berita messing up with the story, continued to support Heronia on the "correct path".
If you truly cared for her, you should have shown her reality, scolded her, and supported her.
This is fucking dumb. Cecil should know that Pii actions aren't wrong, Heronia didn't know about Bertia progress on loosing weight that made Cecil interested in her, neither about unintentional help during epidermic, same goes with people around Bertia being happy instead abused due to her father spoiling her in the story... they just met after graduation and changes Bertia did wasn't noticible to them because they never met personally.
Moreover, Cecil didn't inform Heronia about Berita true actions because he told Courtgain to be quiet whenever she asked him for information and also ordered everyone Cecil knew to not interact with Heronia nor make any contact with "because she gonna drug them" so no wonder neither she nkr Pii knew about anything. This is so dumb...
Thanks for the scanlation!