Mirrored Worlds

Write a story where a character discovers their reflection in a mirror can talk and live an entirely different life.

Mirrors often represent the interface between reality and unreality. How would your character react if their mirror surface becomes a window to an alternate reality, inhabited by their reflection living a radically different life? How are the two realities different? How are they similar? What interactions occur and what lessons are learned? This prompt fuses elements of fantasy, introspection, and exploration of alternative realities.