The Jenchum were a humanoid species, similar in appearance, but different anatomically and physiologically, than humans.
Some Jenchum had the ability to provide positive emotions and remove negative emotions from another; this ability usually emerged at puberty. This process was called the Thrall, and the type of relationship could be sexual, familial, friendship-based or other in nature, but was normally mutually-exclusive. The Painter was one such person who experienced the Thrall.
The Artisans caste was one of the castes in their society.
Upon becoming a master in this caste, a Jenchum was expected to give up his or her entire name, or part of his or her name. An example of this was The Painter. From what the Painter explained, some Jenchum could get away with their first name and profession, i.e. Kaia could become Kaia the Painter.
Superstition led members of this caste to believe if their birth name was spoken after they became a master, they could lose their abilities.
The other castes tended to leave the Artisans caste alone, including the authorities. This allowed the Painter to hide Kari Eriksson from the authorities for so long. (Star Trek: The Prospect Chronicles: "Starry, Starry Night")