Mother and Father Wolf are the first characters we meet in Chapter One. We see Father Wolf, scratching himself like Al Bundy, and Mother Wolf taking care of the cubs. They adhere to the gender norms of the animal kingdom—father wolf goes out to hunt, mama wolf stays in the cave. However, it's Mother Wolf who is the one to be truly feared, like how you don't come between a mama bear and her cubs. Her name is Raksha, which means "The Demon." (1.39).
Mother Wolf ends up being the more colorful, influential character here. She's sarcastic, saying "Indeed, we are very grateful to Shere Khan" (1.11), after talking about how his ineptitude will eventually make her and her family homeless and hungry. And she can say these things because she's so intimidating. We're told that "Shere Khan might have faced Father Wolf, but he could not stand up against mother wolf" (1.40). You go, girl.
When the other wolves cast Mowgli out, Mother Wolf can do nothing to change it, but she continues supporting her hairless little foster son from afar. She's the last person (animal) Mowgli says goodbye to when he leaves, and when he kills Shere Khan, she praises him, saying, "It is well done" (5.106). Then again, she always knew he had it in him.
While Mowgli lives with the Men, Grey Brother is Mowgli's connection to the Jungle. Grey Brother tells Mowgli of Shere Khan's plan, and helps him plot his revenge against the tiger. These three are the only wolves who always stay on Mowgli's side.