LitRPG/VRMMO with slave player characters

LitRPG/VRMMO where one or more of Player-controller characters is enslaved (or pretends to be enslaved) for significant part of story. (for example - D.Rus's AlterWorld does NOT belong here)
It does not matter if character could fix his or her condition by logoff.
English or Russian (if book was translated from Russian to English, it's better to add English version).