Leopold I the Elder is the aged leader of a mouse clan that inhabits a secluded old house in the mountains. He has guided his community for a very long time, and as he grows older, the question of who will succeed him becomes increasingly pressing. His central concern is the future well being of the clan, and he is deeply thoughtful about the responsibility of choosing a worthy successor. He possesses the wisdom and authority that come with his long tenure, and the other mice look up to him with respect. Leopold I is not a physically active character, but his decisions shape the entire story. To resolve his uncertainty about which candidate to choose, he devises a test: he declares that the one who captures the Dragon of Light, a mythical creature said to dwell in the Moon Valley, will become the next leader. This challenge sets the two primary candidates, George and Gerald, on their journey. George is described as kind and thoughtful, while Gerald is energetic and bold, and Leopold I values the strengths of both. His role is primarily that of a mentor and judge. He does not accompany them on the quest but remains behind, awaiting the outcome. Through this test, he hopes to see which mouse demonstrates the qualities best suited to lead. His relationship with both mice is one of a wise elder to younger members of the clan, and he acts as the catalyst for their growth. Over the course of the story, Leopold I himself does not undergo significant personal change, as his function is to initiate and observe the development of the protagonists. His notable abilities include his deep knowledge of the clan's traditions and legends, his careful judgment, and his ability to command the trust of his people.