A scholarly muskrat encountered during the protagonists' journey, Muskrat serves as both philosopher and teacher. He inhabits the natural environment the travelers traverse. Characterized by intense absorption in abstract mathematical and philosophical concepts, he frequently expresses these through complex tangents. His intellectual pursuits favor theoretical exploration over practical application, leading him to neglect immediate physical needs like food during contemplation.

He articulates a personal philosophy called "Muskrat's Much-in-Little," summarized by the equation "Why times How equals What." This framework embodies his attempt to boil down grand universal principles into a single, concise foundational idea, reflecting his scholarly nature. Despite his theoretical expertise, he initially struggles to apply this knowledge practically. He engages with the protagonists' quest to become self-winding, promising to help them achieve mechanical independence. Yet, his approach remains largely abstract, favoring discussions of "pure mathematics" over tangible solutions to their urgent challenges.

His development involves a gradual shift toward practical engagement. While retaining his scholarly identity, he eventually contributes his mechanical skills to aid the protagonists. This includes actively participating in restoring their sought-after dwelling and assisting in the confrontation against their adversary. His journey culminates in finding balance between contemplation and practical need, assuming the role of equipment maintainer at their established residence.