Source: Dark Archive pg.119
Archives of Nethys: Reflection
Stories of malevolent duplicates are commonly told around campfires to frighten companions. In these tales, the duplicate forms after a botched ritual or exposure to a mysterious artifact, and is bent on replacing the creature they've replicated. Most believe such stories to be only that, but such reflection duplicates are real. While some wish to replace their progenitors, others merely want to forge a new life for themselves where no one knows of their origins.
Methods of their creation vary, but all reflections are duplicates of someone else existing in the world. Some are drawn out from literal mirrors, developing a life of their own once set free from the Echoing Pale. Mirror-focused rituals or spells can create independent reflections, whether deliberately or accidentally, as can the magical hazard known as a darkside mirror, which replaces those looking into it with malicious duplicates. Some reflections are created as magical clones by spellcasters, only to turn on their creators or be left adrift, while others arise from polymorph magic gone wrong.
If you want a character who seeks to forge their own identity in the face of their duplicate nature, with a strong tie to another character somewhere out there in the world, you should play a reflection.