Lois McMaster Bujold's nobles had low-born "armsmen" as companions. These were generally bodyguards and assigned on a rotating basis, but particular armsmen could became close companions of a noble. I remember in particular Sergeant Bothari, a senior armsman who was essentially a berserker. Bothari could only keep control of his urge to violence if focused upon protecting someone in his charge. I remember one scene in particular where said charge was Cordelia Vorkosigan ne Naismith, the new wife of his employer. A confirmed pacifist by upbringing and inclination, Cordelia finds herself facing down a rebel of royal blood.