I've been planning this for ages. It began with only Canada as the main character, but it turned into this. I do not own Avatar: The Last Airbender, and I do not own Hetalia. Enjoy!
Chapter 1 (Latvia POV)
I thought that today would be a normal meeting. Terrifying, with Mr. Russia there, and Ms. Belarus holding the knife that she somehow got past security to my neck, but that was completely normal. Estonia managed to keep out of the fray long enough to get away with only a few scratches. Lithuania and I ended up with broken bones, but luckily all three of us managed to sneak away when the knife broke from overuse. According to Ms. Ukraine, it was brand-new from Mr. Switzerland's house. But Ms. Belarus bought a few more from Mr. Switzerland mid-meeting. And they were Swiss Army Knives, which meant that she had two blades and all of the other functions.
By the time the meeting was over, all three of us were beaten and broken from Mr. Russia and Ms. Belarus's abuse.
"P-Prussia!" Lithuania stepped back.
"You thought zat you could escape from my awesomeness?" Prussia shouted to the world.
"Come on, can't you give it a rest…?" Canada said in the background.
"No, because I am awesome!" Prussia declared.
"That doesn't even make sense!" Estonia and I yelled at the same time.
Canada sighed. "And I thought that America had problems…"
"Eh?! You mean that you're not Mr. America?!" Lithuania shouted.
"Who're you?" asked the polar bear that he was carrying.
"I'm Canada…" he said quietly.
"Hey! Jerk-England! Why can't you acknowledge me?" Sealand chased Mr. England obnoxiously.
"Shut up, Sealand," Mr. England muttered.
"Hey, what's this?" Sealand pickpocketed Mr. England's coat, and produced a black candle and a diagram of a … was that a ritual circle?
"Oi! Zese are heretic objects!" Prussia grabbed the candle and the diagram from Sealand's hands. "Zis should be burned ut ze-"
"Give that back!" Mr. England lunged for the paper, but Prussia sidestepped out of his reach.
"Um… Prussia?" Canada whispered. "I really think you should-"
"Kesese!" Prussia took out a cigarette lighter and lit it.
"No! You bloody git, do you have any idea what would happen if-" Mr. England tackled Prussia; taking advantage of the moment where he had to stay still to light the candle, but it was too late. A tiny flickering flame rested upon the wick.
In the confusion, the diagram fluttered to the ground, and began to glow. "Bloody wanker…" Mr. England took out a notepad, scribbled something on it, and tacked it to the wall with one of Ms. Belarus's knives. He removed it, and the pad was still in place. "There." He folded the knife back, and tossed it to me. The circle began to shoot sparks.
Meanwhile, the candle began to emit some sort of force field that surrounded both Prussia and Mr. England. "Oi! Vhat iz going on! Zis iz so un-awesome!" Prussia yelled though it. "Vhy does my chest hurt so much?!"
"Um, Mr. England? What's going on?" asked Lithuania.
"You're the one who needs that the most!" Mr. England said, ignoring Lithuania and Prussia. Was it just me, or was his voice higher than before? It was hard to hear when he was speaking English through that thing. "I don't have time to explain, but just take it! Belarus only used the small blade on that one! It should work fine!"
"What the bloody hell is going on, Jerk-England?!" Sealand yelled.
"Don't worry, whatever you do, make sure that-"
Crackle… Waah! The pentagram had electricity running though it! BOOM!
The light in the room began to fade… my head hurt… I edged toward Sealand… "LATVIAAAAA!"
The world went black.
Ugh… my hands and feet were heavy… someone was dragging me…
"Hey, you! Stop lollygagging and get back in line!"
Was I with some kind of army? Wait… I fainted back there… I coughed.
"Hey, looks like the kid just woke up," someone said.
"Hah… Finally, I'm getting sick of carrying him."
"Hope that kid can pull his own weight!"
There was laughing. I opened my eyes.
I was in… some kind of forest. A group of men in Japanese-like armor were dragging me in chains through the dirt.
"Wh-where am I?!" I cried.
"Ha! The little runt doesn't even know where he is!" There was more laughing.
"Maybe it's a she!" one of them giggled.
"These Earth Kingdom men all look and fight like women, why should their boys be any different?"
Earth Kingdom? Fight like women? Were they at war or something?
"What's your name, little girl?" one of them asked.
"R-Ravis. Ravis Galante," I said, using my human name. It never hurt to use it.
"Ravis? Doesn't sound like an Earth Kingdom name, or a Fire Nation name, for that matter."
"Come to think of it, why are our names similar to Earth Kingdom names?"
"Yeah, I mean, compared to like, Water Tribe and Air Empire  names, Earth Kingdom names are like, identical!"
"Wait… so why did you tie me up like this?!" I stuttered.
All eyes were on me. "Because you were out of the village after curfew and you're definitely not a soldier. Who are you?"
I couldn't help it, this was too stressful! I started to tremble the same way I did around Mr. Russia. Even if they weren't nearly as terrifying…
"I said, who are you?! I asked you a question!"
"I told you, I'm Ravis Galante!" I began to cry.
"Aw man, now you made him cry!" one of them said. He was earnest, not sarcastic at all. "Why would you think he was a spy, anyway? He's only ten, after all."
"I-I'm fifteen!" I blurted out.
There was an awkward pause. "D-Did he just say that he's fifteen?"
"Yeah, I heard ya,"
"Come on, he's no shorter than my kid!"
"Your kid's a girl, and she's nine!"
"Hey, did something just fall over here?"
Whack! Someone emerged from the bushes and hit the guy nearest him. "Take that you Fire Nation-"
BOOM! A grenade! "Hey! Ravis! I'm here to rescue you!" Sealand came out of the forest armed with an assault rifle, with a rocket launcher and a sniper rifle strapped to his back. A pair of handguns was strapped to his legs, and his belt was loaded with grenades. I couldn't see his shirt behind all the ammunition belts . Wow, we didn't get as much equipment in the Red… Army…
"Hey! That's my line! And who are you, anyway?!" the other guy- a boy who looked about my age- shouted back.
"I'm Peter! And I'd like to ask the same to you!" he pointed the rifle at him.
"And why, would I be afraid of a stick?" the guy asked, blowing him off entirely. Something's not right here… he was wearing some kind of… Inuit clothing without the sleeves, and looked totally out of place here with the Japanese armor. And he didn't know what a gun was?
"Because it can do thi-"
"Turēt tālāk!" I shouted in Latvian instinctively (A/N Hold on). "Don't waste ammunition!"
"Ah, you're right," Sealand said, and locked the gun.
"Hold on, who exactly are you, anyway?" the guy asked.
"I'm Peter Kirkland, and this is Ravis Galante!" Sealand said.
"Okay… but that doesn't explain anything!" the guy said.
"Come on, Sokka, he just told us their names, it's not like we can't trust them," a girl emerged from the brush. "I'm Katara," she said to us.
"Katara!" Sokka said with a strain on his voice. He went closer to her. From my listening ability , I heard him say, "They might be Fire Nation spies!"
"Seriously," she said stoically. "Look, Sokka. They can't be older than twelve, and the younger was kidnapped. In chains,"
"Younger? He said that he was fifteen!" ("I am fifteen!" I protested. "Not helping," Sealand replied)
"And you believe that?"
"Sure, if bending exists, then I can believe anything," Sokka said firmly.
"Yeah? Then this isn't logical?" She uncorked a water cask. Water flowed out…of…it…
"Wh-what the bloody hell was that?!" Sealand jumped back about a meter.
"You see!" Sokka said, like he was one-upping her. "They're-"
"Wait a minute… you've never seen bending?" another kid- he was completely bald, with an arrow tattoo- came from out of the trees. Unlike the other kids, he was wearing something vaguely resembling Tibetan or Chinese Buddhist monks robe.
"Th-that's bending?!" Sealand said, startled. "I thought you meant like a- a- branch or something!"
Sokka looked at us suspiciously. "So you've never seen bending, and you threaten me with a stick. Who are you people, anyway?"
I gave a nervous glance at Sealand, and opened my mouth to explain.
FWOOSH! Something came flying out of the bushes, and landed in front of us! "Hey! Look what I found!"
 I used Air Empire instead of Air Nation as taught in Fire Nation Propaganda schools, because 'nation' was already taken. And it's better sounding to take down an empire, right?
The thing with the Earth and Fire nations having similar names stems from the cultures from which they're inspired from. Earth Kingdom=China, Fire Nation=Japan. China introduced writing and stuff to Japan.
 Ammunition belt- I have no idea what it's really called, and I'm too lazy to look it up. It's the thing with bullet ammo covering every inch of a belt-like strap. You can see a similar thing feeding into machine guns.
 Latvia's listening ability- he can tell where Ukraine is by the sound of her… I prefer not to mention it unless necessary. So he can hear whispers if he strains a bit.
Prussia's the one who's most intent on destroying Iggy's stuff because even if Prussia wasn't that religious, and East Germany, too (I don't know, I've never been to Germany!); he was still created for and because of religion, and so is very religious. The Teutonic Knights were a Crusader group, after all. By extent, America is pretty religious (I think that the first colony was founded for Separatists and/or Puritans), but less so, because of the 'freedom of religion' act that's been passed as a part of his becoming of a nation, the lack of a culture to call his own (This is from the perspective of a [Withheld to protect identity]-American), and many religious minorities (not to say that Germany and Prussia don't have any). Plus, much of America's land as it stands today wasn't first settled by pilgrims.
Where are the others? When in the Avatar timeline are they? And what was that candle? Find out… later. Not necessarily next chapter. But eventually.