There should be slaves who find it extremely exciting to be tormented. Or why else does Juliette get her orgasm?
A popular method of torturing victims is "Hot & Cold". The combination of ice and hot water breaks every will.
After he fucks her she has to kneel on the floor with a blindfold and suck his cock.
He first punishes her nipples and then turns on the vibrator.
Now a vibrator is attached to the chair. The slave should have several orgasms.