Each girl is paired with an adult male trainer, or "handler", and together they are referred to as a "fratello" — Italian for "brother". The handler is responsible for the training, welfare and field performance of his charge, and is free to use whatever methods he considers suitable. While these methods vary according to the handler, a common part of each girl's regimen is brainwashing called "conditioning", which produces a deadly assassin with unquestioning loyalty to her handler but, if used excessively, also limits her life span.