The Fairy's Wife Ending is an Ending in Prisoners of the Elder One. It occurs after using the Transfigurative Orb on Lilly.
The spell ends up giving Lilly a penis, and she transforms Erik into a fairy so she can 'try it out'. When both fairies orgasm at the same time, Lilly declares that she and Erik are soulmates, and Erik spends the rest of her days as a submissive wife to the horny Lilly.