Born and raised in the city of Omashu, Bumi was an Earthbender and friend of the Avatar Aang, who often came to visit him. Growing up, he developed a new purpous using the Omashu delivery carts in races, as the "world's greatest super slide". He added to the sceptical Aang that he should not to just see what was there, but instead think about the potential an object could have. He was pleased for being called a "Mad Genius".
Over the years, Bumi grew to become advanced in the art of Earthbending, eventually being crowned the King of Omashu.
At some point he met and trained a wild goat gorilla, taming the animal and keeping it with him as a pet, giving him the name Flopsie.
"The King of Omashu"
After Aang, Katara and Soka were arrested by the Omashu City Guard for the severe destruction of property whilst racing one of the delivery courts, King Bumi was informed of the disturbance and demanded that they be brought before him. However upon seeing the young Airbender, the monarch recognised him to be his old friend, but choosing instead to toy with Aang rather than reveal himself. When called upon to pass judgement for their crimes, Bumi declared that that they should be "throw{n} a feast," to the surprise of all and the annoyance of an irate cabbage salesman.
Hosting his guests at the great feast table, Bumi remarked that many of the people of the city had over indulged with banquets, inquiring if Aang liked his skinless chicken - unaware that his friend was a vegetarian. Instead he turned to Soka and shoved it in his mouth, remarking that he imagined that he would like it instead.
Taking a seat at the head of the table, he politely asked the "young bald one" where he was born, seeing through all of Aang's lies and making jokes at his expense. Adding that the last he had heard of "Kangaroo Island" (where Aang said he was from) it was "really hopping". Yawning he told them that his jokes were making him feel exhausted, adding that it was time for them to retire. Yet before anyone can react, Bumi chucked a chicken wing at Aang, forcing him to display his ability to manipulate wind. He told his astounded guard that they were in the presence of the Avatar, triumphantly asking how he planned to deny his abilities and addressing him by the alias he had used to enter Omashu in the first place.
Katara demanded that they "let {us} leave," only making him pick up a lettuce leaf and make a joke about their current predicament. His tone became more serious as he commanded Aang to compete in three tasks, dismissing them to go to "the newly refurbished chamber" - making it very clear to his guard that he wanted them to be taken to the chamber that had used to been bad until the refurbishments. Continuing off tangent, he mused that they should in fact number the chambers to prevent any more of these conversations from happening, taking another bite of lettuce as they were escorted from the throne room.
Ordering his guards to kidnap Katara and Soka, he summoned Aang to the throne room, demanding to know what he thought about his new robes and adding that he genuinely wanted his opinion. Upon hearing Aang comment that it was "fine", Bumi congratulated him for passing the first test, however noted that the tests that were yet to face were far more taxing. Listening to Aang's refusal to partake, he stated that he had guessed that this eventuality would happen, revealing his hostages and their fate - they are to wear rings of "pure Jennamite" (the creeping crystal) that would encase their whole bodies in the stuff by evening. He felt sorry for doing it, saying it was a "terrible fate" that he could prevent from happening, so long as Aang does agree to his terms.
Gathering on the balcony of an underground cave, Bumi proclaimed the first task was to obtain his "lunchbox key" that was hanging in the centre of a waterfall. As he watched, he sarcastically remarked that nobody had ever climbed the ladder before. He further ridiculed his friend for diving into the waterfall, saying that he should keep doing it and see what happens with each attempt.
Silently impressed by his completion of the task, Bumi told Aang that he needed help with something else before he could allow them to leave. Directing him to the next arena, he asked the Avatar to bring him Flopsie, laughing at the young Airbender's attempts to catch the rabbit, whilst avoiding to be caught by a large goat gorilla. Upon Aang realising that it was in fact the goat gorilla that was Flopsie, Bumi called back his pet and began to play with him, rubbing his belly and cooing about how soft he was.
Chuckling at Aang's pushing for the third and final test, he lead them to the last of his arenas, explaining that the boy had to fight against any opponent he chose himself. He remarked that former should chose wisely though, criticising his decision when he was called on to fight. Shedding his robes, he revealed himself to be a powerful combatant with great abilities at Earthbending. Sending him hurling off the balcony, Bumi jumped into the ring, laughing as he approached his target.
Scolding his friend for underestimating him, he went on to tell the Avatar that he could not take back his decision now it was made, granting him permission to use his bow staff. Using his powers, he scoffed at Aang's reliance on "avoiding" and "evading" attacks, going on to call him predicable. Telling the airbender he would have to fight back, Bumi began pacing back and fourth, summoning sharp stalagmites to slow his opponent down.
Continuing to fight, Bumi kept goading Aang, remarking his attacks were not good enough and were more like a draft that a hurricane. He caused the ground to become like quicksand, dragging Aang into the depths as he struggled to break free as more rocks were manipulated to crush them. However Aang was able to get the upper hand and sends the destroyed wall and balcony fired at him back on his target with a tornado. Held at staff point, Bumi feigns surrender, only to hold a rock above both of their heads and threatens to drop it on them both. However he commended Aang for his abilities and passion, tossing the rock aside, falling back into the sand and manipulating it to travel to the other balcony and join Katara and Soka.
Bumi stated that all Aang had to do was to answer his question, telling the disgruntled hero that the point of his tests were to make him learn. He proceeded with the question, asking Aang to tell him his name, leaving him to guess the answer.
Confronting Bumi in the throne room once again, Aang repeated what his friend had told him all those years ago, once again calling him a "Mad Genius" and embracing him. Dropping the act, he warmly greeted his friend and added that he hadn't changed in all the years he had been trapped in the ice.
Freeing Katara and Soka from the Jemmanite prisons, he revealed that it was in fact rock candy, taking a bite out of it as Katara called him old. Although he was first affronted by this, he later agreed that it was true. When asked why he had not just told him the truth in the first place, Bumi remarked that it was fun to use mess with people, however went on to say that he also had to test Aang to see if he was ready to face the Fire Lord Ozai. He told Aang that he must master all four of the elements, insisting that he should use every technique that he can think of - both conventional and unconventional, in order to succeed and restore the balance of the world. He shared his approval at Aang's friends, stating that with them and Momo, he would complete his quest.
Thanking him for training him with his wisdom, Aang challenged Bumi to a race in the delivery carts, which he quickly snatched.
Appearances:
- "The King of Omashu" (First and Only Appearance of the Series)
