War Against Fuse
The PastIn the wake of the Fusion invasion, Grim was able to slip away from both Billy and Mandy to take a vacation in Orchid Bay in the Past. Unfortunately, Grim's avenue of escape quickly became more trouble than it was worth. Grim has been unable to enjoy his vacation since Fuse's invasion reached the shores of Orchid Bay. His collection of Zuni heads was stolen as a means to create Fusion Grim.
Rumors of Treason
In addition, rumors have been spread about Grim being a traitor, despite the fact that Grim has donated many "Resurrect 'Em" spots to revive fallen players. These rumors started when the player, acting to help Numbuh One, found a tape of Fusion Mandy encountering him, trying to recruit him to their side, though Grim refused. Grim helps the player find Fusion Mandy's lair in the Sand Castle and they defeat her. He is later suspected of being a traitor by Mojo Jojo who asks the player to bring him a Fusion Matter declarifier that Grim would have needed. When it doesn't work, the player brings it to Grim, who uses it to track down Fusion Grim. The player and Grim defeat him and defeat the rumors of Grim's treason.
Finding the Heroes
In spite of these rumors, Dexter trusts Grim to help him find missing heroes who disappeared during the invasion, curious to see if the heroes have fallen in battle. After having his Zuni heads recovered, and utilizing the "Desk Lamp of Hades," Grim reports that the heroes are not in the land of Hades, but are alive somewhere else. Dexter repays Grim for his service by giving him a shrink ray to make more shrunken heads. This leads to the player discovering Fusion Grim in the Hani-Baba Temple. His Fusion was creating new Fusion Matter that affects animals. The player defeats Fusion Grim and receives a Grim Nano.
Grim is being paid by the Whoosh Operators to register kids at Whoosh, the Alpha Whale. The player helps Grim out and they get a cut of his profits.
- He's one of the three NPCs who appear in two Fusion Lairs. The others are Blossom and Dexter.
- Grim is one of the two Nanos whose powers are all Group powers, the other being Darwin.
- Grim has opened a chain of soul-replenishing spas called the "Grim Gardens" that apparently became immensely successful, as evidenced by Princess Morbucks's expressed desire to purchase them.