Following each day spent by Aura in Roya (the fantasy world), Alicia will get her chance to make a mental change in Aura's mind (Alicia's first visit serves as an introduction).
Each mental change costs an indicated amount of Corruption (while controlling Alicia you can't see Aura's Corruption on the menu as you could when playing as Aura, however you can check Corruption by interacting with the object in the middle of the Entrance Chamber).
Mental changes typically trigger real-world scenes that can have the following effects:
Two objects in the Insticts room and the purple crystals in the Main Chamber interact with game mechanics more directly and have no associated scenes.
Scenes may take 2-3 days to trigger, depending on the mental change.
Ending Alicia's turn with an amount of Corruption higher than the current maximum will lead to a "Soul Break", a bad ending for Aura.
Currently nearly all mental changes are required at some point in order to progress. If you are stuck, check every object in every room, and if there are no available changes, then it may be a matter of waiting for a real-world scene to happen on one of the following days. If 3 days have passed without a scene, you're missing a mental change.
Easily-missed changes include switching out Rose for Alicia for going home (Surface Relationships room) and activating happiness sources / drains after setting them (Happiness room). You can identify the latter by the pentagram icon not being lit-up.
But its so cute!: -25 willpower to resist actions that involve dressing up. Unlocked by removing 2 interest books. Doing so requires inserting 1 interest, doing both this and Useless Knowledge requires inserting 3 interests.
Useless Knowledge: 1 extra progress required to finish non-lewd books. Reading speed cannot be buffed. Unlock by removing 2 studying books. Doing so requires inserting 1 interest, doing both this and But It's So Cute! requires inserting 3 interests.
Fashion magazine 1: Unlocks the appearance room. Unlocking it requires you to change Aura's disposition towards Alicia once and insert Alicia in the tutoring relationship. After that the interest will unlock after 3 days.
Shoes 1: To unlock this interest you need to insert Alicia in the going home relationship. Doing that will require you to set a happiness generator to socialization and enable socialization 1, to change Aura's disposition towards Alicia all the way and insert Alicia into the tutoring and evening chat relationships.
Shopping 1: To unlock this interest you need to change Aura's clothing. To do so you need to set a happiness generator to popularity and enable popularity 1. This enables compliments, which you need 4 of to change her clothes. You get the 4 compliments by changing her glasses, hair and shoes (requires shoes 1, see above).
Celebrities 1: To unlock this interest you first have to unlock the interest Fashion Magazine 2. That requires the Estrangement happiness drain to be set to level 1 (requiring 2 interest books to have been removed). In addition to Fashion Magsazine 2 being inserted you have to have changed Aura's shoes to sneakers (requiring the Shoes 1 interest, see above). It also requires the skill But It's So Cute and popularity 1