Originally, Yen Sid owned the brush and used the Paint to bring the world of lost and forgotten characters to life, and Thinner to clean the paint off the brush once finished. Unfortunately, Mickey used the brush to create the Shadow Blot (inadverdantly). A long time later, as the fake Blot kidnaps Mickey, he grabs the brush just before he's sucked into the Wasteland.Mickey drops the brush when he lands, but when the fake Blot challenges him, Mickey picks it up and brandishes it, scaring the Blot off.
Later, when Mickey and his new friend Gus are escaping Dark Beauty Castle, Mickey wonders why the Blot was scared of the brush. Suddenly, Mickey accidentally shoots a stream of Thinner, melting part of a wall. Mickey wonders what else the brush can do and shoots out Paint, restoring the wall. Gus then explains how to control the brush and use it for either good or bad purposes.
Mickey then goes on through his adventure using the brush to paint/erase things and fix Wasteland. When Mickey, Oswald, and Gus blow up the Blot, Mickey is sent back to the Real World and is immediately caught (literally) by an angry Yen Sid. Mickey sheepishly returns the brush.
After Yen Sid forces Mickey to return to his house via the Magic Mirror, the wizard smiles and fires some sort of orange magic out of the brush at the mirror, allowing his former apprentice to reflect on the consequences of his actions. This is the last time in the game that the brush is seen, as Yen Sid returns the mirror to normal using his own magic.
As a weapon
Mickey has the option of using two substances with the brush. Mickey will point and fire the substance at an enemy, NPC, object or building depending on the player's preference. Mickey can also swing the brush to sweep away enemies who get too close to him.
The two main substances:
- Thinner - a malicous substance that destroys aspects of the wasteland, although it can kill enemies and is needed. It also, sadly, increases Mickey's dark side.
- Paint - a heroic substance that improves aspects of the wasteland, and can also turn enemies into allies and improve Mickey's heroic deeds, which is needed in order to gain new allies.