"Will you go penguin sledding with me?"
Aang when he first met Katara (The Boy in the Iceberg)
Aang is the main character and the Avatar from the popular Nickelodeon animated series, Avatar: The Last Airbender. He is born among the race called Air Nomads making him an Airbender. However, he is the last of his kind due to his people being wiped out by the Fire Nation a century ago.
Being the Avatar, he is capable of controlling the Four Classic Elements- Water, Earth, Fire and Air. But he has a lot to learn. On his quest to "bend" all the elements and free the world from the Fire Nation's tyranny, he had many adventures with the Water tribe siblings, Katara and Sokka, the Air Bison named Appa and his pet lemur bat named Momo. Later on his quest he gained two new allies, Toph the Earthbending prodigy and the formerly antagonistic Fire Nation Prince, Zuko.
Aang is a pacifist by nature due to him being taught the non-violent conducts by the Air Nomads all his life. He is also vegetarian. These conducts that were taught to him mirror the real life Buddhist practice of pacifism and vegetarianism because of the belief that all life is sacred and thus must be treated with utter respect.
When Katara came to have a romantic relation with the Dragon Halfa, Terrence Silva, the Airbender developed a dislike and jealousy towards him. Aang initially considered Terrence to be his rival. This is because Aang himself had a romantic relation with Katara. But this rivalry eventually died down and Aang came to accept the relationship between the Waterbender and the Dragon Halfa.
He later lead his own band of heroes called the Magna Force. He and his team first asissted Terrence in fighting Orochimaru while Terrence's team has been controlled by the rogue ninja's spell. Since then, Aang and his team proved to be among Terrence's valuable allies.
Aang was later revealed to have a dark side within him which manifested when he battled the mutant, Juggernaut, in an uncontrollable rage. After Katara calmed him down, Aang spewed out a dark cloud from his mouth which then materialized into his evil counterpart, Devil Aang, who wished to absorb him and his cowardly Shadow counterpart in order to wipe out all life on Earth.
In Vilgax Unleashed and Majestic Guardians Origin, the reason for Aang and Katara's break up was revealed. This is due to Aang's duty as the Avatar caused him to completely neglect Katara. Heartbroken, Katara left Aang. This is the mistake Aang heavily regret ever since.
At the end of Fearless Slayers story: Nerokage Final Battle part 2, Aang was seen kissing an Outer Senshi, Hotaru Tomoe, who became the Airbender's new love interest, indicating that Aang is finally over Katara and has finally been given a second chance in a romantic relationship.
Since Aang and Katara are no longer together, it is unknown what effect this will cause in the future, and it is unknown whether or not Aang will still have children. But the author, GabetheSaiyan, promises to take measures to insure that Aang will still have children regardless, Tenzin will still exist and Air Nomads are guaranteed to repopulate the Earth in the future.