Ouroboros

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An ouroboros is a headmate that originated as an original character created by one or more headmates of a given system, similar to an introject of said original character. The ouroboros then grows and fuel the original character. In the same way, the original character can grow and fuel the ouroboros.

Alternately, if an original character is created that is based on a headmate, and the headmate then introjects traits from that character (i.e. becomes somewhat of a mostive), this can also be the starting point of an ouroboros.

Related Terms
A mostive is a headmate who is an introject of a character created by another member of the system.

If the origin if the ouroboros is not clear - whether the headmate or the original character existed first - they may be called ambigoborous.