Potion of broken Will... (Patreon)

New questline, bad endings, status effects, and other things will be added in the next update. Now, you will be able to lower the Willpower of characters if you obtain a special potion (via a new questline for Euna). However, it is tricky to use, and an overdose can lead to a severe consequence – a Broken Will. For MC, that's a game over, but for your protege, it changes her interactions as she will become a mindless puppet.