To the right of Molly in the gallery...
That's the girl we refer to as the "Nun Puppet". You may remember her from the ending of act 1.
Anyway, she appears in the eldritch part of the main story.
Chastity will offer you relief(?) and if you refuse you miss the scene.
Maybe you did see it and the gallery didn't unlock, you can use the laptop cheat for that, the system is quite wonky.
In the "others" section, the only entry is part of the magic training with the goblin witch.
The second power you unlock with her.