I just posted looking for a Solo as well, so would like to throw my hat into this ring. As you said, this could go many ways...
The Slave does not get sold and must return with the last owner
The Slave is sold and abused
The slave escapes and must be hunted down
The Slave is kidnapped by someone much worse that her last master.
Let me know if this piques your interest.
TexasDM