Coloni is the Old Valyrian word for the lowest social class in Valyrian society, a class made up of unfree commoners, otherwise known as bondsmen or villeins. Their unfree status means that they have a feudal relationship with a lord, often as part of a manor, but they can even be sworn to itinerant, unlanded lords. Even though coloni have the least status of any social class in Valyria, they are still protected by the Great Charter of Valyria, and there are many other reasons why swearing fealty as a non-armiger might appeal to a player.
Much of their status is otherwise determined by the nature of the fealty contract they’ve committed to with their liege. Liege lords can be demanding of those they accept as coloni. Restrictions on travel, on whom one is able to marry, and on what one must wear as clothing typically appear in tenant contracts beyond the simple payment or service commitments that might be the main contributions. Although a colonus can have a number of different arrangements with his liege lord, such as being a land-working serf or even a slave, generally these types of lowly positions will be left to NPCs to occupy. The types of coloni that are most likely to appeal to players to play are socagers, sergeants and servants.
A servant can be anyone who offers work in exchange for tenancy, which includes not only farmers, miners, and woodsmenn, but also skilled artisans who produce for a lord instead of the general public.