Insider

(Namespace: plural glossary)

Type of term	Possible role for a headmate
Synonyms or near-synonyms	Part
Antonyms or near-antonyms	Fronter, host

An insider is a headmate who cannot, should not, or usually does not front. More generally, the connotation is that an insider is more internal to their system than other headmates might be.

Some systems—particularly those either without a host, or with only one host, or consisting entirely of hosts—may refer to all of their headmates as insiders regardless of fronting capability.