Chameleon

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A chameleon is a headmate who steals another headmate's role(s) temporarily. This can be done involuntarily, due to mood, to lift the burden off of others/the body, or even with ill intent. This can be a primary or secondary role.

Related Terms
Chameleons can (but do not have to) be a type of protector or persecutor. A chameleon may also be an emotional funnel or coltenoir, but they are separate roles and are not interchangeable.