The Fairy Princess Ending is an Ending in Prisoners of the Elder One. It occurs after using the Transfigurative Orb on Ixies.
The magic backfires, turning Erik into a fairy princess. Her mind immediately shifts to her new identity, and while she puts up a good fight against Ixies, she still ends up soundly defeated. Ixies then forces Erik (now Esmerelda) to play into her perverted fantasies, eventually delivering her former sister to Ixies.