Mrs. Frisby
Mrs. Frisby is portrayed as a more motherly type figure in the book. Even if she is the typical "mom", dodging cats and getting milk for her kids she is also a mouse with a big heart, helping other animals in need and ultimately being the hero of the book. Her acts of bravery cause her to gain recognition among the animal community and she ultimately helps fight against the genetically engineered rats known as "super rats".
Jenner
Jenner is seen as the hypothetical second leader of the rats of NIMH. Some can refer to him as Nicodemus's alter ego. He only lingers in the mind of Nicodemus but lingers enough to make an impact on Nicodemus's decisions. Jenner is the more cultural perspective of the book. He believes that the rat culture should stay the same and rats should learn how to thrive based on what is taught to them and what they learn. In the book, Jenner is seen in flashbacks and we can see Nicodemus trying to learn from Jenner's mistakes.
Nicodemus
Nicodemus is the tough, stubborn male character in the book. Portrayed as having an eye patch and a long scar along the side of his face, he is the leader of the genetically engineered rats. He gives us an inside look into the society of rats and how their organization operates. Nicodemus is the "smarts" of the colony and is known for giving rhetoric speeches and being the voice of reason.
