Bête Noire was a construct of a spell and a physical incarnation of the Soul Trait Fear, created by Agate Lightvale solely to ensure humans and monsters would never live in peace. She was once Amber and she once had a integrity and justice soul trait (blue and yellow) but now has the FEAR soul (pink) she is a goat monster and talks like Temmie without the randomly uppercase words (because she is a goat monster)