Here is the full list of all 97 Slay the Princess achievements.
Leave a suspicious character in the basement
Freeze in front of a creature on your first meeting
Fall for the rest of your life
Have a voice ruin your happy ending
There's no going back now
Bring the Wounded Wild to Her
Directly attack a suspicious character
Bring the Razor's heart to Her
Allow a sharp foe to vanquish herself
Slay the Princess, and make some enemies along the way
Lure an enemy to advantageous terrain and win
Cannot die cannot die cannot die
Take the bait from your foe
Bring the Adversary to Her
Fight your foe unarmed and go the distance
Unleash the power of pacifism on your foe
Bring the Prisoner's head to Her
Free a prisoner
Bring the Damsel to Her
Your love will set you free
Take on a spirit and destroy it the only way you can.
There are worse fates to suffer than a broken heart
Bring the Apotheosis to Her
Witness your better's ascension
Bring the Fury to Her
Slay your better
And at the end of that path is a cabin
Slay the Princess
Kiss her
Share a thorny prison
Abandon her in a thorny prison
Bring the Moment of Clarity to Her
See what hides behind her mask
It was in your nature
Bring the Witch to Her
It was in her nature
When taken against your will, witness your enemy's freedom
Bring the Wraith to Her
When taken against your will, deal with your enemy the only way you can.
Stuck in a dream without a stair to be seen
Bring the Networked Wild to Her
Embrace your transformation
Some tears can never be mended
Strike the heart from the belly of the beast
Bring the Den to Her
Successfully take the fight to a creature in its den
Successfully flee from a creature in its den
Dodge a creature until you can dodge no longer
Fool a predator by faking your own death
Bring the Drowned Grey to Her
Drown at the hands of a faded spirit.
Dispatch a prisoner
Bring the Tower to Her
Pledge your loyalty to your better.
So have you become nothing once again
This is it
You don't know what you're doing
What can I do to make you stop?
Why have you come back?!
Whatever it is, you'll face it together.
Beget Strange Endings
Bring the Burned Grey to Her
Break the mirror without asking any questions.
Burn at the hands of a faded spirit
Slay an innocent
Bring the Spectre to Her
Pick up a passenger and take her to her destination
Bring the Beast to Her
Free a creature while under extreme duress
Bring the Prisoner to Her
Become your own jailer
Bring the Stranger to Her
When everything is possible, nothing is.
You did it! You saved everyone!
Finish the Game. (The Good Ending doesn't count)
Only new beginnings
We Carve Meaning
Bring the Deconstructed Damsel to Her
All of this is you
Run out of questions
It's all she wanted
Bring the Thorn to Her
You've unraveled
Work through some issues and learn to trust again.
Hand your power to a suspicious character.
Bring the Nightmare to Her
You've withered
Let your terrors loose upon the world
Bring the Razor (Full) to Her
You've grown
Master yourself and vanquish a sharp foe.
Return to your destined path, or face the consequences
You'll know it when you see it.
Bring the Eye of the Needle to Her
Attempt to Out-Wait Your Destiny.
It's you
Free someone who doesn't want to be freed