In "Lil' Porkchop", Billy gets a small fish that Grim grows into a giant. In "Skarred for Life", Bunny Island has been bought out, so General Skarr moves to Endsville, where Billy idiotically tells him of the power of Grim's scythe, so Skarr seeks to own it for himself.
In "Nursery Crimes", Billy has insomnia from eating a lot of cupcakes in the wee hours of the morning, so he has Grim and Mandy tell him a story to get him to sleep. Grim uses a magic storybook to turn Billy and Mandy into characters in the story and they get transported into Fairy Tale World within the book, where chaos ensues. In "My Peeps", Billy's eyesight is faltering and he needs corrective laser surgery to fix the problem, which he doesn't really care for. So Grim tries to do the surgery for him himself... with weird results.
In part one, Billy and Mandy return to the school of sorcery to protect Nigel from the evil Lord Moldybutt. In part two, Billy and Mandy are kidnapped by the Underworld circus owner because in the Underworld humans are valuable circus freaks.
In "Bully Boogie", the Boogie Man comes to visit Grim, much to Grim's chagrin. In "Here Thar Be Dwarves", Billy's picnic outing results in him being placed in the middle of a war between the dwarves and the elves.
In "Which Came First?", when a field trip across the desert is ruined by the school bus' flat tire, Billy, Mandy and Grim go into a cave infested by giant mutant chickens. In "Substitute Teacher", Nergal Junior's first day at his cousin Billy's school results in him being bullied by Sperg, so he transforms into Ms. Butterbean, the school teacher, to exact revenge.
In "Super Zero", Grim grants Billy's wish to be a superhero, and he then goes to fight an Evil Empire. Meanwhile, Grim has to put up with Billy's inept father. In "Sickly Sweet", Billy and Grim put the Mask of the Beast on Mandy's face to coerce her into being a kinder, gentler person. Unfortunately and unsurprisingly, however, it all backfires on them.
In "Bearded Billy", Billy uses Grim's hair tonic on himself to grow a beard, only to resemble a sasquatch when he uses too much of it and is now being hunted for money, with Grim and Mandy as his only hopes. In "The Nerve", Billy robs Mandy of her nerve to get revenge on Sperg for abusing him and his evil self takes over him in the process. Mandy, meanwhile, tries to regain her nerve.
In "Test of Time", Billy uses a supernatural remote control to catch up on his schoolwork... or does he? In "A Kick In the Asgard", during a thunderstorm, Billy somehow gets transported to Asgard, land of the Vikings.
In "Attack of the Clowns", Grim and Mandy try their darnedest to force Billy to get over his fear of clowns, which they think is irrational. But they carry it too far, when he overcomes this fear enough to want to kill clowns. In "Complete and Udder Chaos", Eris cons Billy, Mandy and Grim into owning her Apple of Discord to watch over, since she is supposedly giving up chaos... or is she?
In "Chocolate Sailor", Billy decides to make money by selling mail-order Chocolate Sailor chocolates door to door, only to eat all the chocolate himself, turns into chocolate and eat himself. In "The Good, the Bad, and the Toothless", Billy loses a tooth and meets the Tooth Fairy, but is this mythical character really all he's cracked up to be?
In "That's My Mummy", Billy stubbornly believes he has been put under a Mummy's Curse. In "Toys Will Be Toys", Billy is forced to give up his favorite toys, the Dinobonoids action figures, but first, he persuades Grim to bring his toys to life, so he can play with them one last time.