Disclaimer: I don't own Avatar: the Last Airbender.
A/N: The idea for this came to me during a discussion with a friend a couple days ago about what would happen if people in Avatar didn't have superhuman endurance. This was not intended as a response to recent events, but the timing is perhaps appropriate.
The firebenders had it worst. For one of them a single outburst could mean death to themselves and those around them. A firebender needed to maintain control at all times or face the consequences. The need for such rigid control had a profound impact throughout the Fire Nation, their codes of conduct dictated by the need to avoid giving offense, and their custom of the Agni Kai to resolve disputes far from the homes of innocent bystanders, even their architecture was dictated by the need to prevent and contain fires. But even with these safeguards, there were accidents. An argument would get out of control, or someone would forget their discipline during an act of lovemaking, and the results were often gruesome to behold.
It was worse for their children. Hamaku had once seen a painting of a girl who had set her hair on fire in her exuberance upon receiving a pet turtleduck for her birthday. The girl couldn't have been more than five, and Hamaku could still smell burnt flesh whenever she thought of it. This is why Fire Nation children received preemptive training in firebending, often starting when they were toddlers and continuing until it became clear that they lacked this dubious gift. But even with such safeguards, for many the first manifestation of their talents would also be their last. Hamaku shuddered at a tale she'd heard of a Fire Nation baby left unattended on a bale of hay.
Earth was probably the next most dangerous element. It wouldn't grow and consume like fire did, and unless you triggered an avalanche, it actually took serious effort to kill someone with earthbending. Sure there were lots of stories about an earthbender who lost his temper and demolished a city block. Or about the child who managed to get themselves trapped beneath the earth. Unable to break free. Calling for help uselessly until they eventually suffocated or- well, Hamaku tried not to think about it. In any case, there were stories but Hamaku suspected that the actual frequency of such events was probably pretty low. Although stone ceilings would cause problems now and then if they collapsed on you (probably part of the reason why those who could afford it used wood), it generally took either a very powerful or a very unlucky earthbender to kill themselves in a fit of emotion.
It was at play that earthbending was its most dangerous. In other nations when boys roughhoused with each other, they would come home with cuts or black eyes. When Earth Kingdom boys played rough, they came home with broken bones, crushed limbs, and fractured skulls. It was really a testament to the general hardiness of the earthfolk that any of them at all survived adolescence. Even with proper instruction, training in earthbending could be dangerous. A boulder dropped at the wrong time, or a spike erected in the wrong place could both prove lethal. Hamaku cringed recalling stories of a particular instance in which a student had crushed himself to death trying to learn to make earth armor.
Compared to earth and fire, waterbending was much safer. Hamaku surmised that if the Water Tribes didn't live surrounded by so much snow and didn't use their bending so much, waterbending would be downright safe. Unlike earth and fire, water would rarely kill you by brute force alone. To do serious damage, water generally needed to be concentrated and precisely targeted. While a water whip could be deadly, there was little chance of using one accidentally.
Then Hamaku recalled tales from the Northern Water Tribe. Being surrounded by ice presented new hazards for a young waterbender. An outburst could shatter a building, causing blocks of ice to come crashing down upon the unsuspecting inhabitants, or worse, cracking open the floor and dumping them into the frigid water below. Hamaku shivered in sympathy as she thought of those tribesmen condemned to the icy depths. Then again, with so many benders around and with so many of them healers, such accidents were rarely lethal.
Hamaku knew that most waterbending accidents were of the more mundane variety. A hunter would slip and cut his own hand with the water whip rather than the walrusseal he was trying to butcher. A drunk construction worker would accidentally crush one of his coworkers while trying to erect a new wall. A healer who misdiagnosed her patient might end up killing him rather than helping. The waterbenders knew the dangers of such things, but like everyone else they were only human and now and then accidents would happen.
"Which is why I'm glad I'm and airbender", thought Hamaku with a grin. "Fire, earth, and water can all kill by accident, but air alone is safe. It takes great force to do much with an air blast, much less cause any serious damage. Besides, half of airbending training is about how to flow with the wind and take a fall." Other than some rare cases of murderous rage, Hamaku could hardly think of a single instance in which airbending had killed someone. "It's probably why the Air Nomads have so many benders. Other nations' benders die in accidents, leading to fewer and fewer each generation. Maybe someday they will all die off." Hamaku closed her eyes and imagined how it would be. As the bender population of the other nations dwindled, the airbenders would thrive and her people would one day sail the skies from one side of the world to the other. And thus it was with her thoughts in the clouds and a smile on her face that Hamaku drove her glider at full speed into a cliff.