Katara is still having trouble trusting Zuko due to what happened in the conclusion of Book Two. Determined to make amends with Katara, Zuko readily helps Katara on finding the person responsible for killing her mother, Kya. Aang tries to convince Katara not to take revenge on the man who took her mother, Katara refuses to listen to Aang. It is soon discovered that Kya lied to Yon Rha about being the last water bender and she was only protecting her daughter. Katara spares Yon Rha and she leaves him to grovel in his own pity. Katara forgives Zuko for his past actions towards her and her friends.
—dawsonpersi