Intermediary

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An intermediary is a headmate that focuses on external relationships involving their system. The relationships can be of any kind, such as romantic/platonic/familial, the sysmates involved can be any number, and it can be with a singlet or a partner system. The only defining trait is that the relationship is out-of-system, occurring in shared reality.

Intermediaries can either mediate the relationships, making them better, or sabotage them, making them worse.

Related Terms
Intermediary somewhat functions as a combination of peacemaker and instigator.

This was directly inspired by the term moderator, which is a mediator for intra-system relationships.