Having been accepted by the Gaang, Zuko begins to teach Aang firebending, only to discover that his own firebending has gotten weaker. Realizing that the Fire Nation employ a corrupted version that emphasizes hate and rage, Zuko takes Aang to visit the ruins of the ancient Sun Warrior civilization, where firebending was originally invented, in the hopes of getting back to basics.
- Actually Pretty Funny: Zuko nearly smiles when the others laugh after he reveals the move he and Aang learned is, indeed, a dance.
- Adorkable: Like the previous episode, Zuko gains massive points in this episode; though Aang is no slouch in this either.
- Back-to-Back Badasses: Zuko and Aang stand back to back while learning the power of dragons at the end of the episode.
- Call-Back: The red and blue dragons resemble the ones Zuko dreamed of in Season Two, representing his good and evil sides.
- Character Development: After two seasons, Aang finally overcomes his fear of Firebending. Zuko learns not only of the truth of firebending, but he doesn't have to be angry to command it.
- Chekhov's Gun: The Dragon Dance Aang and Zuko do in the temple to find the gemstone is the key to prove themselves worthy of learning the true ways of Firebending from the last dragons.
- Contemplate Our Navels: Trapped in goo with no way to escape, Zuko suggests this to be a good way to pass the time.
- Continuity Nod: Aang's expression when he firebends, as well as the slo-motion, is virtually identical to when he first firebent in "The Deserter". Only this time he is in full control.
- He refers to Zuko as 'Sifu Hotman'.
- Deadpan Snarker: When Zuko comes to the revelation that true firebending is supposed to be modeled off energy flow, like a sun inside you and asks the chief if they knew this:"Well our civilization is called the Sun Warriors... so, yeah."
- Death Faked for You: Iroh did this for the last two dragons.
- Didn't Want an Adventure: "You had to pick up the glowing egg, didn't you?"
- Don't Touch It, You Idiot!: Aang clearly knows the rules for surviving a Raiders of the Lost Parody.Aang: What exactly is that?
Zuko: It's some kind of mystical gemstone.
Aang: Well, don't touch it!
Zuko: Why not?
Aang: Remember what happened out there with those spikes? I'm just very suspicious of giant, glowing gems sitting on pedestals.
- Durable Deathtrap: Aang nearly gets killed by one. Lampshaded by Zuko when he wonders how century old booby traps could still work. Subverted in that the trap probably wasn't that old...
- Foreshadowing: Zuko points out how unusual it is that the traps are still functioning after so long, foreshadowing the fact that the "lost" civilization isn't so lost at all.
- Hidden Elf Village: The supposedly-extinct Sun Warriors are still living in their apparently ruined city.
- Killed to Uphold the Masquerade: Subverted; after claiming that discovering the continued existence of the Sun Warriors (and the last two dragons) means Zuko and Aang can never leave the tribe, the chieftain then reveals he was just kidding. Then Double Subverted when he rather freakily insists they don't tell anyone what they've seen and learned (since their lives and especially those of the dragons depended on secrecy).
- Last of His Kind: The two dragons protected by the Sun Warriors may be the last dragons alive in the entire world.
- Psychosomatic Superpower Outage: Zuko. For most of his life, he practiced a form of firebending based on rage and hatred - in his case, self-hatred - and now that he's switched sides, his newfound calmness renders him without enough of either to light a candle. Sokka suggests annoying him into firebending again, but Zuko doesn't want to run on that anymore; he thus goes on a quest to learn the origins of firebending - which, as the Fire Nation was once at peace with the world, had to have been far less destructive.
- Ragnarök Proofing: Subverted. An ancient, abandoned city is in pretty good shape, but then it turns out the inhabitants still live there, just in hiding. No proofing, just actual upkeep.
- Raiders of the Lost Parody: The Sun Warriors' city looks a lot like the temple in the opening scene of Raiders of the Lost Ark, complete with booby traps.
- Redemption Demotion: Ultimately inverted, as Zuko proves to be an even better firebender after this episode, but first played straight and discussed when his bending initially becomes much weaker; he used to use hate to fuel his firebending, and his HeelFace Turn has brought him enough peace he can't firebend anymore.Zuko: I bet it's because I changed sides.
- Scenery Porn: The Sun Warriors' city.
- Sins of Our Fathers: Invoked by the Sun Warrior chief, who pretty much says to Zuko that he's off to a bad start with the last two dragons, because Zuko's great-grandfather Fire Lord Sozin was the one who started the act of hunting dragons as a sport, causing the race to go nearly extinct. Eventually subverted when the dragons deem Zuko worthy of learning the true ways of firebending.
- Spikes of Doom: A floor that lowers when a tripwire is triggered, revealing the spikes.
- Stealth Insult: "You know, Zuko, I don't care what everyone else says about you; you're pretty smart." It takes Zuko a few moments to understand the implication.
- Technicolor Fire: The dragons make a tornado of multicolor fire around Aang and Zuko, allowing them to realize what's Firebending's true nature.
- Theme Tune Cameo: The Sun Warriors play the drumbeats from the closing credits music.
- Took a Level in Jerkass: Katara shows this when she rather nastily taunts Zuko for losing his Firebending, puts down his attempts to figure out why, and mocks his new form of firebending. Granted, she plenty good reason to be mad at Zuko: his constant jabs of "barbarian" and "peasant" still ring in her ears - and the part where she did open up to him at the end of the previous season just for him to sucker Aang into taking a bolt of lightning to the back.
- Wall Run: Zuko runs on the wall to get past a trap.
- "World of Cardboard" Speech: Both Aang and Zuko knew from near the start of the episode that their blocks to learning firebending were internal, but it's not until the near the end that they actually give the speech and break through the blocks.