Of all Matt's siblings, Mortimer was perhaps the most unpleasant for the other pups to be around. His unpleasant air hinted of his negative personality, and his tendency to team up with Dennis left the other pups helpless under his grip. Indeed, Mortimer was not a pup to be reckoned with, although his bullying ways were overseen by their parents, who became a strong influence in the headstrong Dennis, who came to recognise Mortimer's deceitful behaviour. The reason for his actions? The personal gain behind his motives? None. Mortimer was just a big bully who enjoyed getting his way. Only Dennis and David (who was the more optimistic of the pups and a compulsive prankster) could ever get along with him.

Mortimer's ways never really changed, the older the pups grew. Sadly, not much is known about Mortimer, or the events leading to the day the pups were drowned by the real estate agent (the owner of Matt's mother). The rest of his life remains a mystery, as are his whereabouts...

Name: Mortimer
Age: ?
Personality: INFP "Performing Noble Service to Aid Society." http://www.personalitypage.com/INFP.html