Lost thing for warlock of zybilna?

In the character creator process rn for my players, one of whom is considering playing a warlock (I suggested of zybilna for ease of exposition for me lmao) she seems interested in her lost item being related to er warlock patronage in some way. She suggested her freedom, her soul being taken for her patron, but the hags wouldn’t have taken something for the sake of a warlock patronage to zybilna. Any ideas for something that could have been taken somewhat in relation to warlock patronage? Or maybe just having something important being taken is what made zybilna offer her patronage to the player in the first place? Just trying to tie it together somehow