Pip appears as a mouse who becomes a close companion to the main protagonist, joining the story in the series' latter half. He provides comic relief through persistent hunger complaints and frequently offers advice, urging his friend toward thoughtful strategy over impulsive swordplay. His full name, Pippin Aloysius Squeak III, incorporates a pun related to his species.

Despite his small stature, Pip delivers practical assistance, notably aiding his companion during the Musketeer trials. Initially self-serving, he is depicted as a thief who steals from Dogtanian upon their first meeting and agrees to become a squire primarily for selfish financial gain. This self-interest deepens when Cardinal Richelieu bribes him to spy on the Musketeers' activities, leading to internal conflict over divided loyalties.

Pip's development reveals a significant shift towards loyalty and courage. He ultimately chooses to support his friend, actively participating in the mission to recover the Queen's stolen diamond necklace and thwart Cardinal Richelieu's plot. A pivotal moment demonstrating his growth occurs when he deliberately intercepts a bullet meant for Dogtanian; his life is saved because the bullet strikes a gold coin he possesses, showcasing both his willingness for self-sacrifice and his resourcefulness. His role balances wordplay, slapstick humor, and moments of unexpected bravery against his earlier self-centered motivations and eventual dedication to the group.