When they were young, Roku and then-Prince Sozin were best friends and shared many things, including a birthday.
On the celebration of their sixteenth birthday, Roku was approached by Fire Sages who proclaimed him to be the
new Avatar, a being who could control all four elements and the link between the physical and spiritual world.
It was Roku's duty to travel the world to master all four elements and provide balance between the four nations but Roku was reluctant to go, saying that everything had changed. Before he left however, Sozin gave him a parting gift in the form of the head piece worn by the Crown Prince of the Fire Nation, an item that Roku would continue to wear for the rest of his life.
Roku's first stop was at the Southern Air Temple where he mastered Airbending and became good friends with a young Monk Gyatso, who would become the guardian of Aang, the future Avatar who would succeed Roku.
Next, he had to master Waterbending, which was tricky for Roku as he was a Firebender and water is the natural opposite of fire. He eventually mastered the element, however and in a short scene, was shown knocking his master into an ice tower with a large tidal wave.
Lastly, Roku had to master Earthbending, which he did while becoming good friends with his master.
Sometime after this, Roku went to the Fire Sages and spent five months on Crecent Island trying to master The Avatar State with Fire Sage Kaja, grandfather of Fire Sage Shyu. Roku became impatient however and used the light from the Winter Solstice sun to force himself into the Avatar State but once he entered it, he couldn't escape and caused significant damage to the temple. He could see his body but couldn't control it but luckily, Fire Sage Kaja reflected the light away from Roku, allowing him to fall out of the Avatar State. As punishment for his reckless actions, Roku's punishment was to rebuild the temple which he did, even using Firebending to create a series of catacombs in the magma beneath the temple.
Twelve years after he left the Fire Nation, Roku finally returned home as a fully realised Avatar and was reunited with Sozin, who was now Firelord and Roku married his childhood crush, Ta Min, with Sozin serving as his best man. On their wedding day, Sozin suggested to Roku that they should share the greatness of the Fire Nation with the world but Roku immediately dismissed the idea, saying that the Four Nations should stay exactly that.
After Roku discovered that Sozin had gone ahead with his plans and invaded territory belonging to the Earth Kingdom, Roku confronted his former
best friend in the palace but Sozin chose to challenge him despite Roku's warning. Sozin was easily defeated through a combination of Air and Earthbending and Roku then entered the Avatar State, destroying the palace before telling Sozin that he'd be spared because of their past friendship, but that he should never move forward with these plans again.
On his home island, thirteen-years later, a volcano began to erupt with incredible power, threatening the entire island. Roku evacuated the island's population but stayed behind along with his dragon, Fang. Roku used his powers to try and stop the eruption and even tried using the Avatar State to stop it but met with little success, unable to work in the hostile conditions and poisonous gases created by the volcano. Luckily, Sozin unexpectedly arrived on his dragon and helps Roku but even this was not enough, forcing the pair to flee from the eruption. However Roku was caught in a cloud of poisonous gas and collapsed before pleading to Sozin to help him but Sozin refused, claiming that with Roku gone, he could carry out his plans without interruption and left Roku to die. As the lava flowed down the volcano to consume the helpless Roku, his loyal dragon Fang flew down to shield him and they both died together.
In the present, Roku appears frequently in spirit form to help guide Aang, giving him advice on what to do next and occasionally helping him defeat his enemies through the Avatar State. Roku is later revealed to be the maternal great-grandfather of Prince Zuko, the current prince of the Fire Nation, which ironically makes Zuko, one of Aang's former enemies, a spiritual family member to Aang.
He later appears in the two hour finale of the series when Aang is searching for an alternative to killing the Firelord, and admits that his own indecisiviness and decision to spare Sozin led to the start of the war, before telling Aang that he must be decisive in his own choice.
Powers and Abilities
Originally, Roku was a Firebender but when he was revealed to be the Avatar, he travelled the world to master the four elements and became a fully realised Avatar at age 28. He had a spiritual companion in the form of his dragon Fang, who provided transport to Roku and allowed him to travel the world with ease.
As the Avatar, Roku was able to enter the Avatar State, a defense mechanism where the Avatar uses all the past knowledge of previous Avatars that granted him a much higher degree of control over the elements.
For more information on Benders and the Avatar, visit the Benders page.