Mole starts as a young underground dweller whose springtime curiosity drives him to abandon his burrow. By the riverbank, he meets Rat, forging an instant bond that cements the river as his new home. Initially impulsive, he makes errors like inexperienced rowing or reckless solo trips into the Wild Wood, yet Rat's guidance cultivates his maturity and loyalty.

His subterranean roots grant him unique appreciation for dens like Badger's, though he remains devoted to aboveground life with Rat. A winter visit to his old home stirs nostalgia, but he chooses not to stay, prioritizing growth and new bonds. His humility surfaces when he sets aside his own longing to revisit his burrow for Rat's comfort.

In later exploits, Mole becomes a steadfast, quietly courageous ally. While less assertive than Badger or Rat in curbing Toad's recklessness, he aids their interventions. During the retaking of Toad Hall, he crafts tactical plans and executes duties resourcefully, proving clever and reliable. As a sensible counter to Toad's impulsiveness, both share enthusiasm for novelty, but Mole heeds wise counsel.

Expanded tales show Mole's enduring loyalty and pragmatism. He shelters the lost otter Portly, balances firm mentorship of his nephew, and joins community efforts to mend Toad's chaos. His bravery, ever tempered by caution, avoids needless risks.