In Romulan, rrh-thanai can be defined as "hostage fostering". Sometimes the making of peace by the exchange of children, each to be brought up in the other's tradition to further understanding and harmony; surety of good behavior: "Don't do this, or your son/daughter will die". Fosterings often start in one context and wind up in another. (TOS - Rihannsu novel: The Romulan Way)