Captive
From wipipedia.org
A captive in bondage or BDSM play is the person who is tied up or imprisoned. Such a person will often, but not always, be a sub or bottom.
In the Gor series of science-fiction novels by John Norman, a "captive" or "prisoner" is someone who is lawfully under the full control of another person (thus not illegitimately kidnapped), yet not legally a slave (see Gor - Dictionary).
