Here's why he's called Grim:
* His appearance: Kevin is small and frail due to his muscular dystrophy. He often wears dark clothing and has a serious, almost brooding demeanor.
* His personality: He's sharp, witty, and can be cynical. He doesn't always sugarcoat things and can be blunt, which can come across as grim to some.
* His past: Kevin has endured a lot of hardship due to his condition, including neglect and bullying. This has left him with a sense of cynicism and a bit of darkness within him.
Even though Kevin is often referred to as Grim, he is also incredibly intelligent, loyal, and fiercely protective of his friends. He just has a different way of expressing himself than other kids.