The Beauty and the Beast unit were a unit of female soldiers who were given special suits to turn them into incredible soldiers, after each one suffered from intense Post Traumatic Stress Disorder caused by horrors of war. This made them potentially invincible soldiers, causing them to be exploited for their skills. Although their damaged minds give them a momentous edge in combat, it is also their greatest weakness.
During the Guns Of The Patriots incident, they were convinced their goal was to destroy Solid Snake, believing it would ease their anguish, and make them "whole" again. Snake fought and defeated each of the members of the unit in turn, usually when they were accompanied by a small unit of the FROGS.
Drebin says that their human selves within can only survive outside of their suits for only a few minutes. This is shown when they come out of their suits and start having a nervous breakdown and reliving their respective traumatic moment. This is most likely due to their fragile mental state.
