Ursa is the wife of Fire Lord Ozai, and the mother of Zuko and Azula. She is respectful and well mannered, and a good mother. She's kind and loving, but will be stern when she needs to be. She's very supportive of Zuko, and realizes that something is wrong with Azula.
On the last day of her residence in the royal palace, (then prince) Ozai and the family were allowed audience with Fire Lord Azulon, Ozai's father. However she and children soon left so that Ozai could get to the point of their meeting. (Which was to revoke Iroh's birthright and crown Ozai instead. Azulon was outraged and refused.) Later that night, Ursa found Azula taunting Zuko about something their dad would do to him. Asking what was going on and getting no useful answer, she sternly led Azula away so they could talk.
In the following early hours while everyone was still asleep, Ursa snuck into Zuko's room and woke him up. Asking him to listen, she told him that "Everything Iíve done, Iíve done to protect you. Remember this Zuko. No matter how things may seem to change, never forget who you are." She hugged him and then slipped out. The next morning she was no where to be found, and Fire Lord Azulon had died. Soon after Ozai was crowned Fire Lord, as it was Azulon's "dying wish". It's not known what happened to Ursa, or where she is.