Katara first met Aang after freeing him from an iceberg. Aang immediately wanted to go penguin sledding with her and Katara was excited to meet and airbender. Sokka did not trust Aang and tried to banish him at one point which upset Katara. While Aang initially lied about being the Avatar, Katara eventually learned the truth and Aang admitted that he did not want to be the Avatar. Katara assured him that the brought hope to the world and joined Aang in his journey to master the elements and save the world.
Aang and Katara quickly became good friends and the former would eventually fall for Katara. Katara was oblivious to his feelings and Aang attempted to tell Katara multiple times but always failed. At one point, the two were trapped in the Cave of Two Lovers together. When their torch was about to run out, the two kissed thinking it would lead them out of the cave. They blushed at each other after they made it out of the cave.
After visiting the spirit library, Appa was stolen by sandbenders. Aang was greatly upset by this. He went into the Avatar State out of anger at one point and Katara calmed him down. Before they got Appa back, Katara reminded Aang that it was okay to be upset. Eventually, Aang attempted to open his chakras in order to master the Avatar State but could not open his last chakra because he would have needed to let go of his attachment to Katara. Aang eventually did so during a battle but was shot down by Azula. Katara healed Aang with spirit water while she was in tears.
Aang later awoke over one month later. While they were traveling through the Fire Nation, Aang and Katara danced at one point and the latter had a lot of fun doing so. Right before the invasion, Aang kissed Katara because he was afraid that he would not return. Katara was shocked but still kissed him back. However, Aang later confronted Katara about her feelings and she said that she was confused. Aang kissed her again which caused her to yell at him and run away. After Aang defeated the Fire Lord, the two kissed passionately in Ba Sing Se and finally became a couple.
Aang and Katara's relationship continued for years later and Katara always joined Aang in helping him deal with world affairs. At some point, they got married and had three children. The one hundred years that Aang spent in the iceberg eventually caught up with him and he passed away, leaving Katara as a widow. Katara would train Aang's next life Korra. Even after seventeen years, she still greatly missed her husband.
Kataang is a very popular ship as it is the endgame ship between the two main characters of the show. It is considered to be the main ship of the series. This ship was initially not nearly as popular as Zutara but it eventually gained in popularity by the series end when it became canon, though not to the point that it surpassed its rival. While many felt that the relationship was forced simply for the sake of the "hero gets the girl trope", a lot of fans celebrated after the Legend of Korra was announced and it was revealed that they had children. A lot of fanon was written about their wedding and their parenting.
BumiBumi is the first son of Aang and Katara and was born as a non-bender. However, he became an airbender after Harmonic Convergence and joined the new Air Nation. Bumi was a commander of the United Forces until he retired and moved in with Tenzin. He is named after Aang's friend Bumi who was the king of Omashu. Bumi was known for being a wild man and likes to tell ridiculous stories of his past.
KyaKya is the second and only daughter Aang and Katara. She is a waterbender and a healer like her mother. Kya has always been a hippie and traveled around the world in order to find herself. However, after Aang passed away, she moved in with Katara to support her. Kya is named after deceased maternal grandmother Kya, who was killed by the Fire Nation. "Secret Tunnel" is her favorite song.
TenzinTenzin is the third son of Aang in Katara. He is a master airbender and was the Air Nomad representative of the United Republic Council until it was dissolved. Tenzin is also Korra's airbending teacher and served as a spiritual guide for her until it was revealed that he could not enter the Spirit World. He is the only of Aang and Katara's children who got married and had children.
- An entire track is dedicated to the relationship between Aang and Katara. It is called "The Avatar's Love" and was unofficially referred to as "Kataang" before the actual name was released.