I had something a little more exciting in mind

In the conclusion of the Hundred Year War, the Fire Nation was successful in using the return of Sozin's Comet to virtually wipe out the Earth Kingdom. The continent was left nearly entirely barren, and the massive loss of plant life and vegetation had disastrous, unforeseen consequences on the global environment. Due to the atmospheric imbalance caused by the sudden lack of forestation, exacerbated by pollution from developing technologies, the polar ice caps melted rapidly, causing sea levels to rise. The Fire Nation archipelago was partially subsumed, and the Fire Lord collapsed shortly thereafter.

Roughly eighty years later, those who continue to survive in the former Earth Kingdom usually do so in isolated groups, which tend to settle around scare resources, such as water. Asami Sato grew up in the remnants of Yu Dao, which by that point was run by an especially vicious and tyrannical warlord. Water and food were scarce and tightly controlled, and her mother died when she was young. Due to her father's value as an engineer, however, she lived in comparative comfort and learned her father's skills, though an accident involving the machinery she helped her father maintain resulted in her losing her right leg below the knee when she was twelve. As she grew older, her father worried her beauty would attract the warlord's attention, and he decided they should try to leave. Asami convinced him to take a number of refugees with them. Though they managed to flee the compound, they were initially pursued, and Hiroshi was killed during the escape. Asami continued on, planning to take the refugees to the only known remaining green place on the continent (the Swamp), but encountered a group led by the new Avatar. The group took in the refugees, and Asami agreed to join the Avatar, who planned to end the warlords' reign and restore the world.

(So, basically, Imperator Asami.)

Asami hadn't planned on staying this long. She had only really meant to drop in and leave her crate, wanting it safely in the Bar as quickly as possible, but then she couldn't really return straight after that drink with Bumi, and waiting had turned into spending a night in a room upstairs, and then a cup of tea the following morning. That done, however, Asami knows it's time to leave, and heads for the door.

It seems that someone else has other ideas, however, as when she tries to open it back into her world, the door won't budge. She tries it from several different angles, but eventually Asami has to concede that the predicament she's heard about from others has finally struck her - she's bound.

Not really sure what to do now, Asami returns to her seat at the Bar. The moment she lowers herself back onto a stool, however, she's provided with something few people get - a reason.

Or, in this case, a key and a folded note indicating a room number.

"What's this?"

There's no further response from the Bar. For a moment, Asami is caught between curiosity and uncertainty, but -

well, it's not actually a struggle that lasts very long. She stands, and wanders back up the stairs to find the room indicated in the note.

It doesn't take her too long. A little wending up the stairs and a hallway she's fairly sure wasn't there the night before, but on the whole, nothing weirder than she's already experienced here. She stops at the right door, stepping close to it as though she hopes to hear through it first (and she... does? But somehow the sounds she pick up seem like they could be produced by many small voices, or the whirring of a machine - that she's not sure which is itself a little unsettling), but then she slips the key into the lock, and turns, opening the door.