Even though Mumble is as ambitious as he is optimistic (which is Very), most of the people who first meet him wouldn't take him for the fighting type. Despite being an introvert and always on the move, he's also very friendly and sociable, ready to greet anyone with a kind smile at a moment's notice and help out almost anyone who asks whenever he can. Not to mention his intense fear of cogs which he isn't always the best at concealing, which, when combined with his soft exterior, makes him seem far better suited to community service than the front lines of any fight.

Despite seeming much more toonanitarian than mercenary, however, Mumble spends most of his time out on the streets taking toontasks as a freelance cog fighter for a living. His dream is to someday become a Resistance Ranger; one of the very best and brightest of troops in the fight against the occupying cogs. Unfortunately, his first several applications as a teen were rejected; even once he managed to get more experience fighting against the cogs on his own, he still had his tendency to freeze up during fights holding him back, and so was ultimately rejected. Ever the optimist, he refused to give up on his dream, and so instead continues to hone his skills and overcome his fears.

Ironically, the source of this motivation is the same as that of his phobia. When he was a toddler, his hometown of Mouseton was gradually occupied and eventually completely overtaken by the cogs. Before he even knew what was happening, Mumble found himself in the thick of an intense cog invasion which nearly cost him his freedom and his parents. It was the relatively new Resistance which launched the efforts to reclaim Mouseton, but even though the toon forces failed to reclaim the city from the cogs completely, Mumble was among the toons rescued by the brave rangers, and after a week spent living in the adoptive care of the Doggenbottom family, his parents were also found and the small family was reunited. But despite the traumatic event embedding a deep fear of the cogs in him, it was also what inspired him to want to help fight the cogs and save Toontown. With the cogs topping the list of Toontown's greatest immediate threats by a longshot, what better way to help the toons of the world than by going after the cog menace?