I know Acacia is currently a dead end, but the game already has a working role model system (like Oriana knowing Celandine is her sister).
We could do the same with Acacia: while she wears the mask, we talk to the demon inside it. If the player knocks the mask off and destroys it in dialogue, she switches to Gareth’s sister role. The AI would play two different characters.
Her mood could shift from rage to fear or calm, just like Gareth calms down after getting angry.
The developer would only need to add 3-4 new facial expressions for her without the mask. And add some roleplay model to ai.
What do you think?