Her appearance is similar to that of a regular brain but with green eyes, a mouth and earrings similar to Vambre's.
Vambre's Brain, in contrast to Vambre herself, is openly loud, rude, sarcastic and selfish. She frequently ridicules Vambre for what she perceives as a lack of common sense, and often provokes her into making self-centered decisions. She is not above putting others in harms way if it'll benefit her and Vambre, or even at times Vambre herself. Unlike Vambre's English accent, Vambre's Brain speaks in a Mid-Atlantic accent. In fact, the only thing Vambre and her Brain genuinly have in common is a love for Veronica Victorius novels.
In the episode "Squirreled Domination", Vambre's Brain finds her pathetic due to her fear of squirrels. When Vambre blames her for her phobia, she comments that her hangups on are her responsibility, whereas her Brain's only job is to tell her when she is hungry. At the end of the episode, she became annoyed when it revealed that Vambre was still afraid of squirrels.
She finally has more of a role in the short named after her. Due to Vambre breaking night by binge-reading Veronica Victorious books, her brain forcefully wakes her up to continue reading. Prohyas tries to wake her up by insulting Veronica Victorious. This causes her brain to try to mock and kill Prohyas until Prohyas finally uses the Sleeping Dragon Magisword on her to knock her cold.
- Body Controlling: She has the ability to take control of Vambre should she herself be too tired to mentally resist.
- Vambre is seemingly aware of the unusual disconnect between herself and her Brain, often calling said Brain into question when things don't line up.
- Unlike Prohyas' Stomach, any action or dialogue made by Vambre's Brain is known and audible only to Vambre herself. In Hideous Hound, Prohyas witnessed a conversation between the two but was unaware of the presence of Vambre's Brain, leaving him visibly confused and disturbed at Vambre seemingly speaking to and threatening nobody.