System. It/its collectively. Adult.
Collective boundaries: don't tease our typos or misproxies. don't predict who we may split. don't try to bring other people into front unless we ask for help with that. don't nag us to sleep. don't make puns/jokes/references with our names/nicknames.
A system is a group of people that reside in one body/mind. You may have heard that systems have a dissociative disorder caused by trauma. This is true in most cases, but rest assured that it's rarely ever as "severe" as Hollywood would have you believe. Trauma refers to how well a person can cope with a stressor, not to any specific abuse. Regardless, the general purpose of a system is to work together to make life easier for each other.
An alter or headmate is a specific member of a system. Alters take turns controlling the body, which is called fronting. The process of a two alters trading front is called switching. Some switches are noticeable, some are not. A host is the alter that fronts most often and takes care of day-to-day life. A split is when a new alter forms.
Some systems have amnesia between alters, meaning that one headmate won't remember what another has done, felt, or said.
Some alters are known as fictives, factives, or introjects, which means they are "based on" fictional characters, real people, or concepts. An introject is not going to act exactly like their source, but may still enjoy being associated with it. They may also have exomemories of the things they've experienced in source.
Some systems have a headspace, a "mind palace" or "imaginary" space where headmates can interact. They can be very simple or very complex. There is commonly a frontroom, where the headspace bodies of the alters fronting can interact.
We call ourselves The Pleiades Cluster. Similarly, if you're unsure who is fronting, or multiple people are fronting and you are addressing all of us, please call us Pleiades. EuryCinth is our host, and in the past has been in front 99% of the time, but as the system becomes more active, Eury has been more inclined to take breaks from front if and when he needs one. Everyone has access to EuryCinth's memories, however spotty those have always been, so anyone you meet will already know who you are and generally carry our collective opinion of you. However, we may not have concrete memory of anyone else's front, especially if we were stressed, sick, et cetera. Because of our minimal dissociative amnesia, any complaint about a headmate not currently in front will find its way to them eventually.
We are an introject-heavy system, and we are quite attached to our sources. We prefer the term headmates, rather than alters.
Online, we use PluralKit or emoji tags to differentiate ourselves. In person, we have fronting bracelets. If we feel comfortable making ourselves known, we will. The others aren't entirely used to using our voice, so be patient as we settle on one.
We do not appreciate people worrying about us or our trauma, or pitying us. Please trust that we are safe now and that we can take care of ourselves and each other.