Observegenic

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Observegenic is an origin term for a headmate or system that spontaneously formed directly from watching or otherwise consuming the media that is their source.

You could potentially refer to it as "Spontaneous Observegenic" if the headmate/system formed more spontaneously, or "Long Term Observegenic" if the headmate/system took longer to develop rather than immediately in reaction to consuming the source, yet still seemed to have no other cause. Although this distinction is not necessary, instead potentially being referred to as just "Observegenic".

History
This term was coined during a discussion in the Pluralpedia discord server. The idea of distinguishing it between more spontaneous or long term was brought up by another system.

Related Terms
Introjects are headmates that have a source.

Fictives are headmates with a fictional source, and factives are headmates with a non-fictional source.