His boss fight acts like a speed run through a level that has rising salt. Making contact with him will not kill Meat Boy. After beating Brownie, Meat Boy will try and save him, but fails as Dr. Fetus keeps pelting him with bricks. Beating him unlocks Chapter 4: Hell.
Brownie appears once again after beating Dr. Fetus and escaping from "his castle". As a boulder is just about to crush Meat Boy, Brownie comes to save him. He is thought to have died as he went down with the island as it was exploding. However, he appears during the credits popping out from his grave and then getting hit by a toilet that comes from Dr. Fetus' castle. The song that is played in this level is called "Fast Track to Browntown".
Before the battle begins, Meat Boy found Bandage Girl tied in the factory and attempts to rescue her. However, Meat Boy's rescue is interrupted by Dr. Fetus, who is relieving himself on a toilet. He then flushes the toilet, creating the fecal matter creature known as Brownie. The feces creature appears and roars at Meat Boy, only to be interrupted by a fart from Dr. Fetus who, after spending time relieving himself on the toilet, presses a button which floods the area with a rising pile of salt. The battle begins.
- He is also available as a playable character in Steam, PS4, Xbox 360 and Wii U versions via a code using an Xbox 360 controller. To play as Brownie, you must have beaten The Salt Factory and input the following code on the controller in the player select screen really quickly without choosing the characters Gish or Alien Hominid for Xbox 360 RB, RB, RB, B, B, B, X or PS4 R2, R2, R2, Circle, Circle, Circle, Square. (PC equivalent of Down, Down, Down, Esc, Esc, Esc, Enter) or Wii U ZR, ZR, ZR, B, B, B, Y. You should hear a voice saying "Push the Buttons!" and then you can select any character and you will be playing as Brownie.
- In the boss fight, Brownie is actually a recording of a developer playing.