Siku and Sura are sibling waterbenders from the Southern Water Tribe and, after Katara, the first known waterbenders to emerge from the tribe since the Fire Nation raids. At their mother's behest, however, they hid their waterbending skills from others, although they did practice in secrecy.
Siku and Sura are young sisters, who lived with their mother in a tiny, inland village east of the capital, well out of sight from the shore and the danger poised by the Southern Raiders during the Hundred Year War. Understandably fearing for their safety, their mother impressed upon them one important rule above all others: to never let anyone know about their waterbending skills, otherwise, at best, "monsters from the Fire Nation" would take them away. This had a lasting effect on the girls.
After the end of the Hundred Year War and three weeks before Sokka and Katara returned home to the South Pole, master waterbender Pakku and his wife, Kanna, discovered Siku and Sura at their village. Having sought out their mother, Pakku demonstrated his own waterbending and after much persuasion, convinced her to allow the elderly couple to bring the sisters with them to the capital, where they would become the first students of Pakku's new waterbending school. However, even though their mother had given her consent to be taught, the girls remained steadfast to her number one safety rule and refused to follow Pakku's lessons, insisting they were not waterbenders at all, though they would bend together when they believed no one was looking. Having the opportunity to at least observe them during these times, Pakku determined that they were very talented for their age, and persisted in trying to train his young students.
Siku and Sura attended a festival hosted by Malina and Maliq with Master Pakku. There, he introduced the two to his prodigy student Katara, who happily greeted them. Pakku told them that Katara was an accomplished waterbender and possibly the finest in the entire world. Katara was modest and told Pakku there was no need to brag, but the old master interrupted her, telling the two kids that it was probably due to their teacher; himself. Katara leaned down and asked the kids how their waterbending lessons were going, to which they responded negatively, claiming they were not even waterbenders before quickly running off. Soon after, Katara and Pakku see them waterbending in secret from a distance.
The next day, Pakku was trying to teach the children how to waterbend, telling them to follow his exact movements, but the sisters did not do anything, reminding him they were not waterbenders. Pakku sighed, wondering if they would pay attention to their special guest, Avatar Aang, who entered the small school along with Katara. Aang started waterbending as Pakku introduced him as the Avatar, much to the young sisters' amazement. Sura asks him if he is really the Avatar, to which he replies that he was, letting Katara continue waterbending when he stopped. Siku asked Katara if she was the Avatar's friend, to which Aang responded that she helped him end the Hundred Year War. Sura was curious as to why Katara had not told them that during the festival. Katara asked them if it would have made a difference and the two sisters agreed that it would have certainly been nicer. Katara kneeled down and asked them if they were finally going to tell them the truth about their waterbending skills. Siku and Sura explained their mother's rule about revealing their waterbending, the danger of Fire Nation soldiers taking them away, and how Pakku's arrival convinced their mother to send them away with him. They ran off, telling Katara that even if it was the Avatar and his friend, no one was going to make them do anything they did not want to.
The next day, Siku and Sura accompanied Aang to go see Sokka and Katara, who were visiting their mother's grave. Sokka and Katara called them over; when they got there, Katara informed them that her mother had passed away. The children offered their condolences, and Katara told them that her mother had also wanted her and her brother to be safe, sacrificing herself so not only so Katara, the Southern Water Tribe's last waterbender at the time, would be spared, but also so that the Southern Water Tribe's bending style could survive into the future. She told Siku and Sura that that's why she felt their own mother had sent them there with Pakku; because she also wanted the tradition to survive. Siku and Sura finally felt confident enough to show her what they could do after that and waterbent a big sculpture-like figure in the air above Kya's grave.
- DiMartino, Michael Dante; Konietzko, Bryan; Yang, Gene Luen (writer), Sasaki of Gurihiru (penciling, inking), Kawano of Gurihiru (colorist), Heisler, Michael; Comicraft (letterer). North and South Part Two (January 25, 2017), Dark Horse Comics.
- DiMartino, Michael Dante; Konietzko, Bryan; Yang, Gene Luen (writer), Sasaki of Gurihiru (penciling, inking), Kawano of Gurihiru (colorist), Heisler, Michael; Comicraft (letterer). North and South Part Three (April 26, 2017), Dark Horse Comics.