In some D/s relationships a partner only submits occasionally and with definite short-term goals, perhaps for an evening or the duration of a party.
In other relationships, there may be an ongoing (not scene- or play-specific) power exchange between or among partners in a committed relationship, often involving love and servitude and enacted in ways throughout the relationship. Some D/s relationships may be compared to the idealized marriages portrayed in older television programs, in which one partner is domestic and service-oriented and the other partner is the provider, protector, and household authority. BDSM may otherwise be deliberately and consciously incorporated into the relationship, or it may focus wholly on power exchange.
Some people may opt for the Master (or Mistress)/slave model, in which consent is negotiated once for a long period and the consent given is generally broader. Slave contracts may be used. Where the contract is in effect continuously, the relationship is referred to as "24/7". The limits of the slave contract can vary widely and extend into other areas of BDSM. Some people opt to be purely "sex slaves", while others who prefer domestic service identify as "service slaves". Some slaves allow their Masters or Mistresses complete latitude as to the demands that can be placed on them. Such a relationship is known as Total Power Exchange or TPE.
People usually only enter into a Master/slave contract after they have known and played with each other for some time, often several years. It can be one of the most difficult relationships in the BDSM world to maintain, and requires special skills and experience.