The Companion System is a modern alternate society where humans and demihumans (demis) live in the same cities. Demis are sapient adults who speak, work and form attachments. Under the Demi Holding Act they are also Registered Holdings, each with a human or institutional Holder.
The law treats them roughly as companion animals are treated in the real world: valued, regulated, owned and without standing of their own. Whatever a demi does, from taking a job to opening a bank account, depends on the Holder's written consent. A demi's worth and daily treatment depend heavily on species class: mythical, rare, common, disfavored or exotic.
The state runs the system through the Civil Placement Office (CPO). Every demi has to live with a human, because someone has to provide for them. Most are matched through standard placement. Four special programs, which the government calls social progress, place demis with offenders, addicts, the mentally ill and the disabled.
Your character. Species, traits, anatomy and history of a player character are entirely the player's to define. The world never assigns them.