The comic The Search explores what happened to Ursa, Zuko's mother, after the events of Avatar: The Last Airbender.

Iroh agreed to join Zuko on his journey to find the Avatar in the beginning, being another outcast of the family. But as the viewers learn, he just did it to spend more time with his nephew ...

Again, she's a great character, but she's not the kind of person who would aid Zuko. Mai has her stuff going on with her family and her brother, and helping Zuko bring peace to the Fire Nation ...