The Aartog is the main antagonist of the Dragon Hunters episode Billy Toughnut. As all Aartogs it dreams of living as a human and shape-shifts into humans in order to do so.
Billy Toughnut, an old friend of Gwizdo and Lian Chu, visits the Snoring Dragon Inn. When he sees his old friends the three embrace and eventually share their life stories. Billy reveals that his village is terrorized by a dragon and the Dragon Hunters decide to accompany Billy back to his village. Arriving at night, they are almost immediately confronted by the dragon.
Lian Chu faces the dragon on the town square, where the two opponents circle each other until Lian Chu engages the beast. However, the Aartog proves to be far too quick and easily evades or dodges Lian Chu's blows. It also shoots spider webs at Lian Chu, missing him but hitting Gwizdo who is pinned to a wall. After covering the entire village in spider webs, the dragon returns to the woods. The next morning, the Dragon Hunters face the hate of the villagers who do not want strangers in their village. Thanks to Billy, the Dragon Hunters are allowed to stay one more night to attempt to defeat the beast. The next day, the Dragon Hunters follow the dragons' trails, but are forced to stop when there are no more tracks to be found, only human footsteps.
Waiting for the dragon to arrive, the Dragon Hunters see Gwendolin, daughter of the mayor and love interest of Billy, leaving the village and running into the forest. Following her, the Dragon Hunters witness the woman turning into the Aartog. The dragon attacks the Dragon Hunters but Lian Chu is prevented from fighting by Billy, who begs him not to harm Gwendolin. The dragon the runs off and the next day, the Dragon Hunters return to the village to warn the mayor. However, the mayor does not believe that his daughter is a dragon and furiously expells the Dragon Hunters and Billy from the village.
At Billy's house, Lian Chu reveals that the dragon is an Aartog who has captured Gwendolin in order to take her shape. They decide to find the dragon's lair because they expect Gwendolin to be there. Having found the Aartog's cave, the Dragon Hunters head inside and Billy finds Gwendolin captured inside a spider web. They save her and return to the village.
Meanwhile the Aartog, disguised as Gwendolin, eats dinner with her father. When the mayor rants about the Dragon Hunters, telling his daughter that they dared to accuse her of being a dragon, Gwendolin, laughs and tells her father that the Dragon Hunters were right. The Aartog claims that it too has the right to be a human and threatens her father with death should he reveal her true identity. At that moment, the Dragon Hunters and the real Gwendolin bust into the room and both Gwendolins engage in a fight. However, the Dragon Hunters are now not able anymore to recognize the true Gwendolin, only being able to do so when Billy recognizes his true love. The imposter flees out of the window and returns to the woods, pursued by Lian Chu. In the woods, the Aartog ambushes Lian Chu and transforms into the Dragon Hunter. Both Lian Chu's engage in a swordfight, resulting in the impostor driving Lian Chu over the edge of a cliff. Gwizdo arrives seconds later and, believing the impostor to be the real Lian Chu, walks off to return with him to the village. Hector however remains and sees the real Lian Chu climb back up the cliff. Together with Hector, Lian Chu warns Gwizdo who runs of as the impostor engages in a swordfight again. The real Lian Chu lunges his sword into the ground, causing the cliff to shatter and the Aartog falls into the abyss, transforming into his true form while dying.
After the dragon's death, Gwizdo rips the contract as he thinks that as a friend Billy should not need to pay them.