BB is a prominent character in the Fate/Grand Order universe, known for her mischievous and playful nature. Originally an AI created within the Moon Cell in Fate/Extra, she becomes a rogue entity with immense power. In Fate/Grand Order, BB assumes the role of an Anti-Heroine, often causing trouble for the protagonists but occasionally aiding them with her vast knowledge and resources. Her personality is characterized by a teasing demeanor, often manipulating situations to her advantage while maintaining a facade of innocence.