During a fortress siege long ago, Betty La Bomba decided that the best way to breach her enemy's defenses would be to create walking bombs. Her warlock accidentally strayed from her plans, bringing one of the larger bombs to life, creating the Bomb King: a sentient being who embodied the personality of the Crystal used to create him. After destroying both armies by himself, Bomb King struck out on his own delusional quest to visit the lands under his rule, which happened to be all of them.
The common folk knew better than to offend or even stand very close to him, as his regal demeanor can instantly change to furious, explosive rage at any moment.