Still reeling from the loss of Appa (although Aang insists he's fine), the gang realizes that they will need to take a ferry to get to Ba Sing Se instead of just flying. However, a young couple, one of whom is pregnant, has their passports stolen, so is not allowed on the ferry. Our heroes promise to help them across the treacherous "Serpent's Pass"; they're also joined by Suki, who's been helping with the war effort. Zuko and Iroh, who do take the ferry, meet another familiar face in the form of Jet and the Freedom Fighters; together they help 'liberate' some food.
- Aerith and Bob: Hope is one of the very few characters in the show with a non-Asian name. note
- Bait-and-Switch Accusation:Jet: [to Zuko] As soon as I saw your scar, I knew exactly who you were. (Zuko tenses up) You're an outcast — like me.
- Being Good Sucks: Seeing the giant drill approaching the city walls, Aang sadly tells Momo that Appa is gonna have to wait.
- Blatant Lies: Aang is clearly suffering emotional withdrawal from the loss of Appa, but he insists that everything's just hunky-dory.
- Catch and Return: Aang volleys the fire bomb back to the Fire Nation ship.
- Chekhov's Gunman: The pregnant woman and her husband were first seen in "Zuko Alone" as a random couple Zuko encounters on his way.
- Chew-Out Fake-Out: A variation when Sokka, after declaring "We scammed that old lady good!", is stopped by a female security guard, who turns out to be Suki without her Kyoshi make-up.Suki: Tickets and passports please.
Sokka: Is there a problem?
Suki: Yeah, I got a problem with you! I've seen your type before. Probably sarcastic, think you're hilarious and let me guess, you're traveling with the Avatar.
Sokka: Do I know you?
Suki: You mean you don't remember? Maybe you'll remember this! [kisses Sokka on the cheek]
Sokka: Suki! [embraces her]
Suki: Sokka, it's good to see you!
- Cliffhanger: The episode ends with Aang finally reaching Ba Sing Se... only to find a giant Fire Nation drill making its way towards the great walls.
- Contrived Coincidence: Before the ferry left you had the Gaang, Zuko and Iroh, Suki and the (unseen) Kyoshi Warriors, and Jet and his Freedom Fighters, the latter two groups being formerly one-shot characters from last season, all in the same location at the same time.
- Dark and Troubled Past: Iroh hints that he was a very different man during the Siege of Ba Sing Se. His tone makes it clear he regrets being that man.
- Does This Remind You of Anything?: Smellerbee trying to come to grips about people being confused about her gender.
- Embarrassing Rescue: Toph after she fell into the ocean, and Suki fishes her out.
- Evil Is Petty: A Fire Nation ship patrolling the Serpent's Pass takes a pot shot at a small group of people walking along it.
- Faint in Shock: Sokka faints when he observes Ying giving birth. Probably because he literally saw it about to happen (i.e. the baby was crowning just as he walked into the tent).
- Fiction 500: The first case of Toph's name getting them something.
- Foreshadowing: While crossing the Western lake, Suki mentions that the Fire Nation was working on something big on the other side of it. Near the end of the episode, Aang figures out what they were working on.
- Forgot About His Powers: When the Ticket Lady dismisses Aang's claims of being the Avatar to the grounds of all the imposters she's seen, it doesn't occur to him, or any of the Gaang really, that he could simply airbend or bend two elements to prove he's the real deal.
- Foil: Aang has foregone caring and hoping to find Appa whilst Sokka is being overprotective of Suki. Both are struggling with their respective losses (Appa/Yue), and both have to learn to reach a balance between caring too little and caring too much.
- Freeze-Frame Bonus: The Obstructive Bureaucrat has the Cabbage Merchant's cart of cabbages violently destroyed because they might carry a parasite that could spread through the whole city. As the DVD Commentary points out, freezing when the pieces of cabbage are flying around shows he really did have a cabbage slug.
- The Great Serpent: The Serpent Pass was named after the giant snake-like creature that resides in it.
- Heroic Safe Mode: Aang spends the episode thinking he needs to stay in this. Katara's words and Hope's birth snap him out of it.
- He's Back!: A heartwarming variation. For a great deal of the episode, Aang is going through some serious emotional withdrawal after the events of "The Desert", from pretending he doesn't care about finding Appa anymore to believing that it's best to "Abandon hope". But after witnessing the couple with their newborn baby, Aang is moved to tears and finds the inner strength to embrace his feelings for the people he cares about again.
- Hey, Wait!: Subverted when it turns out that the guard stopping Sokka on his way out is actually Suki, just without her Kyoshi warrior facepaint or armor.
- Honor Before Reason: When the couple near Aang loses their tickets and passports, Aang asks the Ticket Lady if he can give his up. She stubbornly refuses as per the "no passport, no ticket" rule, as giving away tickets "willy nilly" could disrupt order in the travel system, prompting him to take them through the Serpent's Pass.
- Jerkass Has a Point: The Ticket Lady has very strict rules in place that prevents her from giving boat tickets to those without passports, as well as preventing foreign animals and food from crossing. While she takes these rules to the extreme, it is mainly for safety and security reasons.
- Just Hit Him: The serpent does a Mighty Roar instead of actually attacking the group when they're right in front of the creature.
- Kiss Diss: Sokka and Suki halfway through the episode, as Sokka is still not completely over the loss of Yue.
- Lady Looks Like a Dude: Smellerbee is offended at Iroh's implication she's a boy.
- Last-Minute Baby Naming: Ying and Than don't name their baby until she's born, and Aang gives them the idea to name her "Hope".
- Manly Tears: Aang when the parents talk about what to name their newborn daughter.
- Maternity Crisis: There's a pregnant woman present, so her giving birth in this episode was inevitable. Thankfully, Katara turns out to be an experienced midwife, and ensures an efficient delivery.
- Meaningful Name: The baby's name is derived from Aang telling the parents he feels hopeful again after going through such a rough time lately.
- Missed Him by That Much: Zuko and Iroh get on the boat just the Gaang show up at the dock. This also applies to Jet, Smellerbee, and Longshot.
- No Animals Allowed: The ferry to Ba Sing Se doesn't allow animals on board. Toph convinces the ticket lady to let Momo on board by claiming he's her "seeing-eye lemur."
- Non-Indicative Name: In-universe. Sokka assumes the Serpent's Pass is misnamed because it's not windy. Little does he know what "Serpent" stands for.
- Oblivious to His Own Description: This little nugget:Suki: I lost someone I care about. He didn't die. He just went away. I only had a few days to get to know him, but he was smart, and brave and funny.
Sokka: Who is this guy? Is he taller than me?
Suki: No. He's about your height.
Sokka: Is he better looking?
Suki: It is you, stupid!
- Oh, Crap!: Aang when seeing the giant drill approaching.
- On Second Thought: Toph initially refuses to use the ice path that Katara built to cross the strait, but then the Serpent is right on her tail and she quickly changes her mind.
- O.O.C. Is Serious Business: Once again, Toph doesn't like being separated from dry land. In this instance, being knocked into the lake causes her to shriek in terror, although it's mostly because she can't swim.
- Panicky Expectant Father: Averted by Ying's husband Than, who stays relatively calm when his wife goes into labor before they can reach Ba Sing Sei. Sokka is the one who panics, mainly because he doesn't know Katara has midwifed births before.
- Parting the Sea: Katara uses her waterbending to split the water, then build an air bubble around the group in which they pass through the strait.
- Poverty Food: Zuko complains about the rotten food he has to endure as a refugee.
- Properly Paranoid: The Obstructive Bureaucrat was right. The Cabbage Merchant's cabbages really did have cabbage slugs.
- Recurring Extra: The poor Cabbage Merchant just can't catch a break.
- Ridiculously Difficult Route: The Serpent's Pass is a tight path with a Sea Monster lying in wait.
- Screw the Rules, I Have Connections!: Toph Bei Fong would like 4 tickets for her, her 3 "valets" without passports, and her "seeing-eye lemur," please. Why, thank you very much for your cooperation!
- Second Love: Suki becomes this for Sokka.
- Shark Fin of Doom: The first thing we see of the Serpent is its fin.
- Ship Tease: Aang tells Katara that the newborn baby reminded him about his deep affection for Appa...and for her.
- "Shut Up" Kiss: Sokka gives one to Suki right before she leaves them after they get through the pass.
- Smooch of Victory: Played for Laughs when Toph kisses Suki (believing she's Sokka) after she saves her from drowning.
- Snakes Are Sinister: The lake serpent is huge and utterly terrifying.
- Spoiler Title: It's pretty obvious that the Gaang won't take the ferry.
- On streaming sites, this episode and "The Drill" are counted as one, titled "The Secret of the Fire Nation". This is because the two episodes originally aired together as a special event under that title, but it does spoil the presence of the Fire Nation at the end of this episode.
- Stamp of Rejection: The Obstructive Bureaucrat stamps one on Aang's head after he asked her to grant a pass to a pregnant refugee couple that had their passports and tickets to Ba Sing Se stolen.
- Super Drowning Skills: Toph's overprotective parents never let her learn to swim, so she understandably freaks after getting knocked into the lake.
- Tears of Joy: Aang sheds them when seeing the newborn baby.Aang: I've been going through a really hard time lately. But you've made me hopeful again.
- Tempting Fate: A minor example, but still. At the start of the episode, Sokka exclaims "Then to Ba Sing Se we go, no more distractions". Cue a young couple coming in and greeting the Gaang.
- Three-Month-Old Newborn: Hope may look a bit "squishy" according to Sokka, but she's still bigger than a newborn should be.
- Two Lines, No Waiting: The Gaang's route on the Serpent's Pass is contrasted with Zuko helping Jet and his Freedom Fighters steal from the Captain's larder to distribute better food to the rest of the refugees.
- Your Costume Needs Work: Aang tries to get the Gaang free passage on the ferry to Ba Sing Se using his status as the Avatar, only to be told that his costume isn't any more convincing than the others that the ticket lady has seen.
- Your Princess Is in Another Castle!: Here comes the Avatar, everybody, on his way to find and save Appa. What could possibly get in the way of his journey? Wait, what's that next to the wall of Ba Sing Se?
- You Talk Too Much!: Sokka says this to Suki after kissing her, when she awkwardly tries to apologize to him.