Allagian

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Allagian is a term for a headmate, usually an introject, who had a different gender, orientation, or similar identity before becoming a system member than they do now that they are one.

Their previous identity is called their pre-allagian gender/orientation/etc. and their current identity is called their post-allagian gender/orientation/etc.

For example, an allagian system member may have been pansexual before becoming a system member, but is asexual now.

From the Greek allagí meaning “change”.

Reference
Gaitive may be considered a specific type of allagian, and an allagian introject may be considered nonsimilous.