In the water:

Sonic, Katara, and Sokka were on a wooden boat as Sokka was catching fish.
Sonic: (Man, I hate water... Oh yeah, you might be asking, how did I get here? Well...?)

Flashback:
Sonic falls from the sky from a portal as he lands on the snow.
Two people notices a blue creature on the snow.
Katara: What was that?
Katara runs to the blue creature.
Sokka: Hey, wait!
Katara and Sokka sees a blue creature stuck in the snow.
Sokka: Okay, what is that?
Katara: Don't know, but it looks like a animal.
Sokka pokes the blue creature on its head as he starts to move.
Sokka: Whoa!
Sonic gets his head off the snow as he sees two people in front of him.
Sonic: Huh? Who are you?
Sokka: What the?! That thing just talked!
Katara: What are you?
Sonic: Me? I'm a hedgehog.
Katara: A hedgehog?
Sonic: Yep. Name's Sonic, Sonic the Hedgehog. You two are?
Katara: I'm Katara, and this is Sokka.
Sokka: What exactly are you doing here?
Sonic: I don't know. I just fell from a portal.
Katara: A portal?
Sonic: Yep. I'm not from this world.
Sokka: What?!
Katara: So you were transported here from a portal and you're from a different world?
Sonic: Yep.
Sokka: Can I just say something quick? Why are you naked?!
Sonic: I'm a hedgehog.
Sokka: But people here will be embarrassed!
Sonic: Really? Nobody hasn't said anything about it.
Katara: I'll give you some cloths, okay?
Sonic: No, you don't need to. I can have my own.
Sonic snaps his fingers as his outfit appears.
Sonic wears it as the two were surprised.
Katara: Whoa...
Sokka: Okay, I'm gonna say this right now. That was epic!
Sonic: Hehe. You guys think I can stay somewhere?
Katara: Yes there's somewhere you can stay. Come with us.
Sonic: Thanks.
Sokka: What? We don't even know you.
Sonic: You will once you get along with me better. Anyway, what happened here? It looks like there's stuff that have been destroyed.
Katara: Well, you see...

Few hours later:
Sonic has met the other people from the camp and Katara talked to Sonic about what happened and bending.
Katara: There has been a war going on for the past 100 years.
Sonic: 100 years?
Katara: Yeah. Back then, all four nations lived together in harmony. Water, earth, fire, and air. But, everything changed when the fire nation attacked.
Sonic: The fire nation attack?
Katara: The Fire nation has supposedly killed all the airbenders. There were the ones who started this war. Because of that, our mother died.
Sonic: Oh...
The fire nation has killed benders for the past 100 years, and I'm the only waterbender here.
Sonic: The only waterbender?
Katara: Yeah, but I'm certain that an Avatar will come and save the world.
Sonic: I see...
Katara: Also, there's an unique thing we use that is called bending.
Sonic: Bending?
Katara: Yes. By using your hands and feet, each nation has their own elements and can use it.
Sonic: Whoa, that's cool.
Sonic's stomach grumbles.
Sonic: Man, I'm hungry...
Katara: Oh, here.
Katara gives Sonic some bread.
Sonic: Thanks, Katara.
Sonic eats the bread.
Sokka: So, what exactly can you do?
Sonic: I'm the fastest thing alive.
Sokka: The fastest what?
Sonic zooms behind Sokka.
Sokka: Whoa! How did you-
Sonic: Told ya.
Katara: That's amazing.
Sonic: Hehe.
Sokka: (Oh great...) Katara, let's go catch some fish. We're gonna need some food.
Sokka leaves.
Katara: Okay. Wanna come along?
Sonic: Umm.. I don't know...
Katara: Is something wrong?
Sonic: The thing is, I can't swim.
Katara: You can't swim? It's fine. You'll be in a boat, so you'll be fine.
Sonic: Thanks.

End of flashback:
Sokka: It's not getting away from me this time. Watch and learn you two, this is how you catch a fish.
Sokka has the equipment for catching the fish as Katara was using her waterbending to put the fish in a bubble.
Sonic: Whoa, that's cool.
Katara: Right? Sokka, look?
Sokka: Shh. Katara, you're going to scare it away.
Katara: But Sokka, I caught one!
Sonic: Something's wrong with your body.
Katara: Oh, I can't properly control my bending.
Sonic: Oh.
Katara couldn't control it as Sokka hits the bubble causing the fish to go away and the water to fall on his head.
Sokka: Why is it that every time you play with magic water, I get soaked?
Sonic: What's wrong? Does he not have any bending?
Katara: Theres some people that have it, and some that have not.
Sonic: Oh.
Sokka: Yeah, that water magic thing.
Katara: It's not magic, it's waterbending and it's-
Sokka: Yeah, yeah, an ancient artifact, unique to our culture, blah, blah, blah. Look, I'm just saying that if I had your powers, I'd keep my weirdness to myself.
Sonic: Wow.
Katara: You're calling me weird? I'm not the one who makes muscles of myself every time I see my reflection in the water.

Sonic: Hahaha!
Sokka: Hey! Be quiet!
Sonic: Sorry, it's just you were doing it just now! Hahaha!
Sokka: Ha ha, very funny.
A current was happening as it pulls the boat in to where the ice were.
Sonic: Whoa!
Sokka maneuvers the boat going left and right avoiding the ice.
Katara: Watch out!
Sonic: Uh oh!
Sokka moves left, but the ice was closing together as it breaks the boat.
Sonic: Jump!
Sonic and the two jumps onto the ice.
Sonic: Phew, that was close.
Katara: You called that left?
Sokka: You don't like my steering? Well maybe you should've waterbended us out of the ice.
Katara: So it's my fault?
Sonic: Uhh...
Sokka: I knew I should've left you home. Leave it to a girl to screw things up.
Sonic: Uhh Sokka, I don't think that's-
Katara gets angry.
Katara: You are the most sexist, immature, nut brained... I'm embarrassed to be related to you!
Katara's waterbending causes the huge ice to start breaking up.
Sonic: Katara...?
Katara: Ever since mom died, I've been doing all the work around camp while you were out playing soldier!
Sokka: Uhh... Katara?
Katara: I even washed all the cloths! Have you ever smelled your dirty socks? Let me tell you, not pleasant!
Sonic: Umm, Katara...?
Sokka: Katara! Settle down!
Katara: No! That's it, I'm done helping you! From now on, you're on your own!
Sonic: Katara, I don't think this is the time for arguing, but look behind you!
Katara: Huh?
Katara's waterbending gets stronger as it breaks the huge ice causing waves to blow them away.
Everyone: Wahh!
Sonic: (You gotta be kidding me...)
Sonic and the two holds on to the ice.

Sokka: Okay, you've gone from weird to freakish, Katara.
Katara: You mean I did that?
Sokka: Yep. Congratulations.
Sonic: Uhh, guys, what's glowing under the water?
Katara, Sokka: Huh?
The three sees something glowing in the water as a huge iceberg rises up.
Sokka: What the?!
Sonic sees someone with a arrow tatoo inside the huge iceberg.

Sonic: Hmm?
Katara: What is it?
Sonic: It looks like there's someone inside it.
Katara: You're right.
The person glows bright as it was alive.
Katara: It's alive! We have to help!
Sonic: Count me in!
Sonic and Katara jumps from the ice towards it.
Sokka: Hey, you two! Get back here! We don't know what that thing is!
Katara hits the iceberg with Sokka's weapon as Sonic was homing attack it.
Sokka: You can turn yourself into a ball?
Sonic: Yep.
Sonic and Katara keeps hitting it, as it breaks causing wind to blow the two away.
Katara: Wahh!
Sonic: Whoa!
A bright light shines from above as a ship was sailing in the water. A person sees a bright light in the distance.

Zuko: Finally. Uncle, do you realize what this means?
Iroh: I won't get to finish my game?
Zuko: It means my search is about to come to an end.
Iroh sighs.
Zuko: That light came from an incredibly powerful source. It has to be him!
Iroh: Or it's just a celestial light. We've been down this road before, prince Zuko. I don't want you to get too excited over nothing. Please sit. Why don't you enjoy a nice cup of calming tea?
Zuko: I don't need any calming tea! I need to capture the Avatar! Hound man! Head a course for the light!
The smoke clears out as Sonic and the two sees a person walking up.

Sonic: Guy, stay behind me.
The boy's tatoo was glowing as it disappears. The boy the falls as Sonic catches him.
Sonic: Whoa, that was close.
Sokka pokes the boy's head.
Katara: Stop it!
The boy slowly wakes up as he sees two people in front of him.
Sonic: Hey there.
Boy: I need to ask you something...
Sonic: Hmm?
Katara: What?
Boy: Please come closer...
Katara: What is it?
Boy: Will you two go penguin sledding with me?
Sonic: Penguin sledding?
Katara: Uhh... sure, I guess.
Sonic: Well, if it sounds fun, then sure.
Sokka: Wahhh!
Boy: What's going on here?
Sokka: You tell us! How did you get in the ice?! And why aren't you frozen?!
Boy: I'm not sure.
Sonic: That's kinda weird.
Sokka: You're one to talk.
Sonic: Oh, please.
The boy hears a noise in the distance as he climbs up the ice seeing a big bison.
Boy: Appa! Are you alright?
Appa was sleeping as the boy tries to wake him up.
Boy: Wake up, buddy.
The boy tries to open its mouth up as it wakes up.
Sonic and the two sees the big creature as they were surprised.

Sonic: Whoa.
Sokka: What is that thing?!
Boy: It's Appa, my flying bison.
Sokka: Right... And this is Katara, my flying sister.
Sonic: Ok, that was kinda good. And I'm Sonic.
Appa begins to sneeze as it shoots snot on Sokka.
Sokka: Ahhhhh!
Sonic: Ill...
Boy: Don't worry, It'll wash out.
Sokka: Yuck!
Boy: So, do you guys live around here?
Sonic: Not me. I'm from-
Sokka: Don't answer! Did you see that crazy bolt of light? He was probably trying to signal the fire navy!
Sonic: Huh?
Katara: *Sarcastic* Oh, I'm sure he's a spy from the fire navy, you can tell by that evil look in his eyes. The paranoid one is my brother, Sokka. You've never told us your name.
Sonic: Yeah, what is your name?
Boy: I'm Aaaahhhhchuuu!
The boy sneezes as he flies up in the air causing wind as he comes back down.
Sonic: Whoa...
Aang: I'm Aang.
Sokka: You just sneezed, and flew ten feet in the air!
Aang: Really? It felt higher than that.
Sonic: Wait, he was using wind, so does that mean he's a-
Katara: You're an airbender.
Sonic: Oh.
Aang: Sure am.
Sokka: Giant light beams, flying bison, an airbender, a talking blue hedgehog, I think I got the midnight sun madness. I'm going home to where stuff makes sense.
Sonic: And how do you suppose you do that when we're by all this water?
Aang: Well if you guys are stuck, Appa and I can give you a lift.
Sonic: Great!
Aang: Hop on!
Katara: We'll love for a ride!
Sonic and Katara hops on Appa.
Sokka: Oh no. I am not getting on that fluffy snuffy snot monster.
Katara: Are you hoping some other kind of monster will come along and give you a ride home, you know, before you freeze to death?
Sonic: She got you there, Sokka.
Sokka: Ugh...
Sokka gets on Appa as Sonic was standing in the front.
Katara: Aren't you gonna sit down?
Sonic: Nah, I'm fine. I always do this.
Aang: Okay, guys! First time flyers, hang on tight! Appa, yip, yip!
Appa jumps in the air as it goes in the water.
Aang: C'mon, Appa! Yip, yip!
Sokka: Wow.... That was truly amazing.
Aang: Appa's just tired. A little rest, he'll be soaring through the sky. You'll see.
Sonic: Alright then.
Aang keeps looking at Katara as he was smiling.
Katara: Why are you smiling at me like that?
Aang: O-Oh, I was smiling?
Sokka: Ugh...

With the fire navy:
Iroh: I'm going to bed now. Yep, a man needs his rest. Prince Zuko, you need some sleep. Even if you're right, and the Avatar is alive, you won't find him. Your father, grand father, and great grand father all tried and failed.
Zuko: Because their honor didn't hinge on the Avatar's capture. Mine does. This coward's hundred years of hiding are over, and I won't stop until I find him.

That's it for this chapter. And yes, it's not the full episode. I decided to do half of it if it's okay with you guys. The other half will be here soon. Peace!!!