I already completed the good ending so I know more or less how the questline goes.
What I wanted to ask was, at what point in the quest can I trigger the neutral ending and how do I do that?
Is there more than one ending? I know there's the 'stab her trauma' ending, and I seem to recall the game calling that the neutral ending. *goes to check*
Oh huh, no, you're right. That's the good ending apparently. I wonder how you get a worse ending... probably it's a 'ghost princess moves on to afterlife' ending. Maybe while diving in to go get the knife, if you don't kill her inner doubts, she resolves to do something different at the end. Her inner monologues were very 'I shouldn't be here' until you killed them all and she finally went "Since I got this chance, I should enjoy it".
The library fairy tends to tease alternate endings though, and apparently she got lines for that one according to this changelog note: "-Added dialogues for Sonnet "Faerie Tales" book, regarding the 2 Ghost Princess endings "