Shattering Expectations
Plurality encompasses a range of experiences poorly defined by any one conception.
Whether you're talking to a system, or considering what's inside yourself, here's what not to take for granted.
Numbers
A body and an individual is not necessarily a 1:1 relationship. Conversely, not everyone under the plural umbrella can be modelled as "multiple people in a body". Plurality is a queerness of cardinality, encompassing all the fuzzy lines where we can't confidently state that 1:1 relationship in all senses and cases. These system configurations are diverse, and represent a variety of lived experiences - whether it's a system of ~7, 31, 2, 1,000,000, or 1*.
Names
As pluralfolk, we always lay between the extremes of our bodies containing one person, and of being a multiple-bodied group of people. A system might have names for each of their members, an overall system name but no member names, a system name and member names, many names per member, two headmates that share a name, a few members without names, patterned names that reflect how the system works, and much more! A newly self-discovered system might keep their old name to refer to the system, to refer to a specific headmate, or to refer to any arbitrary headmate in a kind of "hey, you!" fashion - it's all up to them.
Gender
Like genderqueers necessitate understanding gender as distinct from sex, pluralfolk necessitate understanding gender as distinct from the body. While both have their exceptions, different parts of a system can vary in that "gut feeling" of gender, and so might use unique pronouns, and hold a different conception of their transness: a trans person discovering their systemhood may have system members aligned to their old gender; so are they cis, trans twice, or just trans once? that's for them to conceptualise.
Relationships
A notable variance in system configuration is in what bleeds over (or stays constant) between headmates. The answer always lies between the extremes, but where exactly varies - memory might be totally contiguous, or almost completely individualised. Headmates may share beliefs, but differ in opinions - share interests, but differ in tastes - share gender, but differ in sexuality! With this in mind, systems may feel that relationships to others exist mostly across all headmates, individualised to each headmate, or somewhere in between - rapport accrued by one headmate always "smearing" across others to some extent.
Appearance
In most of our society, how you appear is a key part of your identity and individuality. Pluralfolk can rarely make exclusive claim to the appearance of the body, so self-perception often differs between headmates - whether different styles or proportions on the body, or a totally different body entirely, a shared understanding of how someone appears on this meta-physical level is often key to social connection.
Humanity
Like furries, therians, otherkin, and other nonhuman subcultures online and otherwise, the metaphysical appearance of a system member need not be human. Without an obvious "human starting point" in the form of the body to dispel, pluralfolk often reach this conclusion intuitively and without fanfare. Anthropomorphic animals, robots and machines, spirits, monsters, or computer software - the form (metaphysical appearance) of a system member helps convey and express what makes them unique.
Causality
To fully understand a system, it's key to understand how the system understands themselves. As covered in More Than One, many systems hold belief in why exactly they are plural - reasons accidental, deliberate, spiritual, or of course absent! These causal beliefs are of course not unique to pluralfolk - nobody knows why they're conscious, but many choose to hold faith.
Words
As pluralfolk, we model the language used to describe our internal experiences on that of the outside world. This language is not meant to be meaningless to an outsider, but it can't be taken at face value - as its meaning is being inscribed by the system conveying it.
A Minotaur headmate is not The Bull of Minos, but might resemble them. A "sexual relationship" between headmates can sound quite serious - but in sharing a body with a libido, many see this as largely unimpactful and obviously implied. System members with the names of fictional characters could be widely invested in displaying their attitudes and mannerisms, or they just might like the look! System members that call eachother siblings might refer to a resemblance, bond, or rivalry - but could easily be using sibling to mean headmate. System members that are described as instinctive animals, or as unintelligent, old, naive, or young would all appear to present striking, complicating, sometimes dangerous issues in the outside world - but as with the above, this language refers to nuanced experiences that only the individual system themselves can convey the ins and outs of. It's only through this per-system interpretation of the language we use that others can gain a genuine understanding of our experiences.