Grim is very much a servant to his wife Hildy Gloom, although the two seem to be in a very loving relationship. As shown in "The Itsy Bitsy Spider Fighters," he has a fear of spiders and ladybugs. His ancestor once ruled Jollywood until the Seven Founding Fathers defeated him.
Grim isn't the brightest spark in Jollywood. He doesn't always comprehend situations as quickly as Hildy does. He can also be a bit dim-witted, especially when he steals a goose from a giant and has no idea it's the one that lays golden eggs.
However, what he lacks in intelligence, Grim compensates for in love for his wife. Often going to great lengths to please Hildy, Grim seems to live only to please her. He seeks her approval, and while he isn't always successful, he never stops trying. The pair are clearly dedicated to one another. Their signature "nose-kiss" is a perfect example.
Grim is often exploited by Hildy. She often loses her patience with Grim when he cannot grasp her brilliant plans to take over Jollywood. However, it has been shown that she cannot live without him. In the episode, "Grim the Genius," Hildy becomes devastated when Grim becomes smart enough to think for himself. When his sweet disposition goes sour, Hildy allows the 7D to take back the Smarty-Pants Stone. She whimpers that "I just want my Grimmy-whimmy back."
- Grim and Hildy's names are derived from Grimhilde, the Evil Queen's alternate name that was given in early publicity materials.
- Grim was originally going to have green hair instead of blue.