A regent is in charge of ruling a realm when a king or lord is underage or incapable of ruling due to injury or illness. The regent's service normally ends when the ruler comes of age on their sixteenth birthday (or eighteen for Mer), or when the ruler recovers from their injury. The regent is often the young ruler's parent or other close relative.
Regents of lords from great Houses might style themselves the 'Protector' or 'Lord Protector' of their lord's given region (e.g., the 'Protector of Calambar' for a regent ruling in the name of the Lord of Skywatch). In Alinor, royal regents have additionally taken the title 'Protector of the Isles', a title usually reserved for the king.