A fetter is totally not a Shadow from Persona 4 a physical representation of a person's flaws, insecurities and fears. They only occur in people who have experienced great struggle with trauma or mental illness - but a person who is mentally ill or who goes through trauma is not guaranteed to have a fetter. It all depends on how gracefully they deal with the hand they've been dealt in life. At a certain level of trauma or struggle, though, it becomes understandable how someone couldn't possibly just get back up and keep going without serious damage to their essential being. Especially if that trauma has never been talked about, aired out or dealt with in any way.

Fetters come in threes: a primal first stage (the earliest incarnation of the person's problems), a second stage (generally an unstable being, the struggle between many different harmful forms of coping) and a third stage (the final stage of the person's issues).

First-stage and second-stage fetters can experience a large deal of change and development (in any direction, good or bad, mind you) but third-stage fetters are more or less stuck. The problems a third-stage fetter are problems that cannot be cured or fixed permanently, but these problems are meant to be lived with. As you might have guessed, a third-stage fetter can either end up fairly well-off, or very very unhealthy.

Of course, the vessel (that is, the person) can experience change and growth at any phase in their lives, but... The position of their third-stage fetter tends to be an extremely accurate signifier of which direction they're going to grow in. Dramatic changes of perspective don't tend to happen to people whose third-stage fetters have fully manifested.

They live in environments rife with symbolism related to the vessel's fears, insecurities, trauma and struggles in life, and these environments tend to be dangerous more often than not. Hell, fetters tend to be dangerous more often than not, but it all depends on which one you're dealing with and how polite you are, how gentle you are in handling them and their problems. Most of the time, if you treat them well, they will treat you well, volatile as most of them tend to be.

Fetters are almost always named after the scientific genus names of flowers (example: Artemisia, Lavendula, Asphodel) with fairly rare exceptions (example: Snowbelle, Belladonna). Their given/"birth" name will always be the name of a flower or plant in some respect, but some fetters have been known to take on different names out of a matter of preference. Of course, refer to them with the names they ask to be referred by. Some fetters just want to be referred to with their title, which is always formatted as "The ______" (example: The Snow King, The Hostess, The Sun).