Tristan and Isolde
Celtic/medieval romance
The love potion makes literal what is psychological: Anima projection experienced as fate, as divine compulsion, as love that destroys the social order because it serves a deeper order.
The love potion IS the projection. You don't choose to project. It happens to you.
The pattern underneath: The Anima / Animus. The qualities you've assigned to 'the other' rather than owning as part of yourself.