after failing to complete the second trial in the Sanctuary you hear a familiar voice, it's rem, after a bit of talking she gets close and almost kisses you but you know it isn't her, you get very angry and tell this imposter to reveal themselves

Carmillia: T-this isn't... what I was told... to expect...

She transforms back into her original form

Carmilla: I-im Carmilla, t-the Witch of lust. N-nice to meet you...

the place around you turns into a grass field aka the witch's tea party