dissociative identity disorder, or d.i.d, is a disorder where there are two or more distinct personalities or personality states present in one individual. it used to be called “multiple personality disorder” but that terminology is now out of date.
other specified dissociate disorder, or osdd, is a disorder where an individual has significant levels of dissociation, but does not meet the criteria for another dissociative disorder. osdd1 in particular is often described as “partial d.i.d”.
both d.i.d and osdd1 are trauma based disorders and form as a response to childhood trauma occuring from birth to about age 9. these two disorders are the only disorders by which a system, or collection of personalities, is formed. as system formation is a response to trauma, one cannot be a system without some form of abuse taking place in one's childhood, even though not all parts or alters may remember it.
alters and parts
an “alter” or “part” is a member of a system, a personality or personality state. while not technically or legally people, systems will often refer to them as such. it often makes more sense to explain it that way to highlight the dissociation and differences between one alter and another. alters may have different perceptions of age, gender, sexuality, species, and what they look like that may differ from that of the body in which they reside. alters may also have memories of things that did not happen to the body. these are referred to as “pseudomemories” and are often associated with introjects.
introjects are alters that are influenced by outside sources, such as famous people or fictional characters. “fictives” are introjects from fictional media, whereas “factives” are sourced from a person in real life. an introject's “source” is the media or person the introject is based from. often times introjects will identify with that person or character, but it is equally likely that they won't. introjects may or may not behave like their source. either way, it is important to treat introjects like you would any other person or alter.
system jobs
not every system will have an alter to fill each role. sometimes alters will take on multiple roles, or have no clear role. the roles listed here are only the most common ones; there are plenty of other roles an alter may take on.
HOST: the primary face of the system, usually either the one who fronts the most or identifies most with the body
PROTECTOR: shields the system from futher trauma and/or defends against abusers
LITTLE or MIDDLE: alters who percieve themselves or act as if they are children or teenagers
CARETAKER: an alter that takes care of the system in one way or another
PERSECUTOR: often harms the system or body in some way as a misguided attempt to shield them from further trauma
TRAUMA or MEMORY HOLDER: an alter who remembers particular memories or trauma that the system has gone through
system functioning
