The Knights of Nanteos were made up of a previous civilizations highest military officers. All of the knights were Kabbalist who were kicked out of their previous civilization due to religious fervor. The Knights decided that it was divine providence they were exiled to Dirio and committed themselves to helping the people of Dirio.
Any freeborn man above 18 may join the Knights. However, it is a hard process. They still maintain their military roots. Recruits must pass special ops grade training, must pass an intelligence test which gauges their ability to learn and comprehend the amount of tradition and secret knowledge of the knights, and must be a good citizen of whatever nation they live in. Should one member of the Knights say they don't want a recruit to join then they recruit is not allowed in. They can try to join once in every 4 years.
The Knights of Nanteos maintain a degree of autonomy from the government of the Kingdom of Nanteos. The knights were granted the power to arrest any fugitive by King Marcus I. This power was once again given to the Knights in the age of the Proclamation by the Department of Jurisprudence. In some cases such as the 1st Avalonian War the Knights have fought independently from the Kingdom.
All Knights are referred to by sir.