Mr. Huggles first appeared in the issue "The Twelve Portals". He didn't last as long in the book series as he did in the cartoon. He was eventually run over by a car.
He was a gift to Will from Matt Olsen, but Will's mother forces Will to give Mr. Huggles to Irma Lair. Irma eventually hands him over to Hay Lin. Unfortunatly, Mr. Huggles escapes from his cage and creates chaos in "The Silver Dragon". Thanks to that, Hay Lin gives Mr. Huggles to Taranee Cook, but Taranee's father has an allergy to fur. Taranee gives Mr. Huggles to Cornelia Hale. However, Lillian Hale frees Mr. Huggles so he can meet Napoleon, but both pets end up making chaos. Cornelia gives Mr. Huggles to Elyon Brown, but Mr. Huggles escapes again and is finally returned to Matt.
Mr. Huggles was eventually turned into Khor, the Destroyer by Nerissa Crossnic. Khor was the first of Nerissa's Four Knights of Destruction to be created. Transformed into a hulking, muscled humanoid, he feeds on anger. Even in this form, Mr. Huggles still has the qualities of a loyal pet. In the Knights of Destruction's final battle with the Guardians he is freed from Nerissa's control and reverts to his original dormouse form.
- Taranee recognizes Mr. Huggles as the species Muscardinus Avellanarius, or the common Hazel Door Mouse, found primarily in Europe.