10 years after the Grundel was captured,  a second Grundel started to pick up where the first Grundel had left off. This Grundel was later revealed to be a victim of the first Grundel named Jack. Jack had been a friend of the Extreme Ghostbuster Kylie Griffin. The two of them had an encounter with the first Grundel as children. Although Kylie was too scared to answer the creature's call, the seven year old Jack had willingly let the creature in and he too became a Grundel.  Unlike the other victims of the Grundel, Jack did not transform back to his original form after the Grundel was captured. The Grundel had sensed that Jack had a strong will and was extremely impressed with him, but also knew that it would take more effort to convert Jack than his usual targets, so the Grundel had placed Jack in a cocoon that shielded him from the effects of the captured Grundel. Within the cocoon, Jack remained a Grundel and grew and matured into a full grown Grundel.
10 years later, the cocoon was exposed from the tree it was placed in during a lightning storm, releasing Jack as the new Grundel. As soon as he was released, Jack started to follow in the footsteps of his predecessor. The original Grundel later got loose from the Containment Unit and the two Grundels teamed up to find Roland's younger brother Casey Jackson, who easily allowed the Grundels in. After the Grundel was captured a second time, Jack was finally returned to human form. Kylie pledged to Jack she and the team would help him find his parents.
- ↑ Grundel (1997). Extreme Ghostbusters- Grundelesque (1997) (DVD ts. 09:37-09:49). Sony Pictures Home Entertainment. Grundel says: "Kylie, you were strong. You refused to come out and play so I instead I had to pay your little friend Jack a visit."
- ↑ Egon Spengler (1997). Extreme Ghostbusters- Grundelesque (1997) (DVD ts. 06:30-06:38). Sony Pictures Home Entertainment. Egon says: "That would be my first thought, Kylie but it's highly unlikely. You see, there's only one Grundel and Ray, Winston, Peter, and I trapped it 10 years ago."
- ↑ Kylie Griffin (1997). Extreme Ghostbusters- Grundelesque (1997) (DVD ts. 10:55-11:11). Sony Pictures Home Entertainment. Kylie says: "A friend. My only friend. He was seven years old when he disappeared. Jack never came back. Nobody believed my story. I must have blocked it from my memory until now."