Fan vessel concept: The Horror (a self loathing princess)
Buckle up, this is a long one.
This is in some ways the gentle princesses equivalent of the specter, you have to go downstairs without the knife to immediately attempt to save her without hesitating at all. When you do the princess actually ask you if you know why she's locked up down here. You can either hesitate and remain silent, which leads to the normal chain of events and the Damsel, or you can be completely honest and tell her that you were told she was going to destroy the world. As always she thinks the notion is ridiculous.
You cut her free and when the narrator tries to take over your body there's a new option, one created by your unwavering determination to save the princess, one that can push back against him so completely that the princess doesn't even have to kill you. The Voice of the Hero hands the blade to the princess to make sure that the narrator doesn't get another chance like that and the two of you leave the cabin, the narrator ranting and raveing the whole time.
You go up the stairs and out the cabin door, and as you do, the narrator begins to fade away. Then, the world also starts to fade. The princess is shocked. She looks around at the world disappearing and asks if you're doing this? If you knew this would happen? If... she's doing this? Then it really hits her, she truly realizes that she is destroying this world, she feels the cold and the horror of the situation, and before the world can disappear fully, she tries to stop it by taking your blade and plunging it into her own chest, she is dead before the Shifting Mound can take her.
It's too little too late, and the world continues to fade out until you are left standing in nothingness the only thing around you, the dead body of the princess. Having never even seen the mirror and having made a vessel that Shifty cannot use.
And get the choice to either stay here for eternity resulting in getting one of the five stages of grief scenes where Shifty takes you and yells at you and all that.
Or just like in the good ending, you can kill yourself. Take the blade from the body of The Princess and stab yourself
Then you wake up on the path in the woods but rather than the narrator's voice, the first thing you hear is an echoey distorted version of the princesses: "you're on a path in the woods, and at the end of that path is a cabin, in the basement of that cabin is a princess, you are here to slay her" her voice breaks, a sob cutting through, "please..."
The narrator is confused, and for the first time we see him suspicious. He immediately picks up on that you have had to have been here before, because unlike other chapter twos this beginning is too different for him, the woods are as they should be but the princess taking his place even for a moment is something he can't ignore.
He suspicious that she is asking you to slay her, he tries to hide it but he's clearly wondering if maybe she has some sort of actual plan to use her death to escape. He can't comprehend that she might actually want to die, tying with both his mistrust of The Princess and his belief that anything is better than oblivion. He can't comprehend that Princess might want to make the same 'noble' sacrifice that he did.
The princess on the other hand serves as a voice for this chapter, she is able to hear the voices and the narrator throughout the chapter, (or maybe the piece of her within you does) and is adamant that you need to kill her. Her doing it didn't work. It has to be you.
I think you would get the voice of the contrarian as well, because as much as I love him in stranger, I didn't even know he had his own chapter until I found a list of all the routes after firt playingthe game, that's been fixed a bit in the pristine cut, but I still feel like he needs a more content heavy dedicated chapter.
Narrator is busy trying to both insist that you need to slay the princess, but also imply that maybe you shouldn't do it now because it seems like killing her is what she wants and it'll probably let her escape somehow, while still trying not to put too dangerous of an idea in your head. He's torn caught in a loop of reverse reverse psychology.
As you move forward towards the cabin, the narrator eventually settles on the position that you need to do something about the princess but just stabbing her in the heart with the pristine blade is clearly what she wants somehow and you shouldn't go through with it, you'll have to find another way. "Maybe burn the cabin down or feed her poison, maybe there's a bottomless pit we can drop her in. It feels like that would work."
The princess insists that nothing else will work, it has to be with the blade and it has to be Quiet doing it.
The hero is sad but is on team kill the princess with the blade having seen what freeing her did and listening to her wishes, where as the contrarian is the one who still insists on trying to save her. He believes there has to be a way, and despite everyone disagreeing with him, he keeps pushing for it.
Inside the cabin is cordoned off, wooden planks covering the windows, all haphazardly nailed into place, as if in a rush. The door is barred and also nailed shut. Covered in signs that tell you to keep out, and stay away for your own safety.
The blade is in a case with a sign referring to it that says 'in case of emergencies take this'
The princess and hero want you to take the blade, the narrator doesn't, and surprisingly the contrarian wants you to pick up the blade.
And then he tells you to throw it out the window.
If you do that, or choose to leave the blade, the princess freaks out. Calling you a monster that's doomed of the world and many other things before her voice goes silent, and you feel her presence leave your head.
She still goes silent if you take it and don't throw it out but only after thanking you, telling you how to open the door.
The princess tells you she's sorry for the inconvenience she just wanted to make sure she couldn't leave, just in case she ever wanted to.
You slowly pluck the nails from the door, and as it opens the princesses the voice leaves your head, "see you soon..."
You head down the stairs. The narrator describes the basement as a constraining place, if the princess lives here slaying her would be a mercy.
No matter which of the stair dialogue options you pick the princess responds with something more or less like.
"I know you're here we were just talking"
When you get downstairs the basement is a more classical dungeon, prison bars separating you and the princess, you can see her through them, she has taken on an appearance with elements invoking the idea of Eldritch horror, she has an extra set of eyes on her face and her hair looks more like tendrils, moving on their own.
Her dress looks more like she is coated in a dark liquid that flows off of her rather than a proper gown. The hand that you had cut off to free her, has been replaced with a long set of tentacles, them wrapped around a ring hammered into the wall rather than her being shackled. She's the one holding herself here.
You ask if you can approach, she tells you the key is on the table beside you, and you can decide to take the key and leave her in the basement (which triggers the shifting mound to take her), or open it and talk to her.
This is a princess who has the kindness of the damsel, but has seen the destruction she can bring to the world and is terrified of it. She believes she can only hurt people, and rather than embracing it like other vessels she she quarantined herself.
She believes her death is the only way to protect everyone. She trusts you to be the hero for everyone else like you were for her, but a part of her is suspicious that you knew that letting her out would really end the world and intend to, but you're the only person who can do this so she has to trust you.
If you come down without the blade, or in the process of your conversation get rid of the blade somehow she will panic and ask you why you did that.
You can tell her that you don't want to kill her and you think there must be another way.
In response she is scared and confused, driven by her emotions her tentacles unwrapped from the ring, and they reach out and grab you, constricting you while she asks how you can have seen what you've seen and still think there's something else for her, that she can be anything else.
In the process she accidentally crushes you, and as you die she has an emotional breakdown, believing that she shouldn't have trusted you with this, and that this is proof that she can only hurt people, when you die you get an alternate version of The Thorn, one with different dialogue (like how the fury has different dialogue depending on if you came from the tower or the adversary.)
If you manage to slowly convince her that she can be freed safely she will come with you and hesitate as you near the door, eventually she will step outside, and things will seem fine for a moment, she will smile, and then the world will start to fade again, and she looks at you with hurt in her eyes, heartbroken at what she thinks is all her fears being proven right. And then the hands take her.
If you try to forcibly free her, by cutting the tentacles that are serving as her shackle she will take it as you actively trying to end the world, and it will kill you taking you to whatever her unique chapter 3 would be, (probably something involving her trying to keep you both chained up forever since killing either of you doesn't seem to work.) You'd also get the voice of the stubborn for that chapter.
If you listen to the narrator, and go against the princesses wishes by trying to kill her in some way other than the blade, (I don't know maybe there's a bottomless pit in her cell or something,) it will net you "the good ending"
Eventually, the contrarian will decide to kill you, and if you don't have the blade, he will have you jump into the bottomless pit
This also bring you to that unique chapter 3, except with the voice of the cold.
I think she would make for a remorseful heart