Season 2, episode 1 of Avatar: The Last Airbender got pretty much everyone moving. Episode 2, "A Fight, Once Begun," picks up things from there, and it is the Toph episode. Yes, the one fans of the original series have been waiting for since the season was announced, and it does well to reward that anticipation more often than not.
It also runs three separate storylines that each feel like they belong in the same episode, without any of them getting obviously shortchanged. The title of the episode comes from a line Ozai says in a flashback to a young Zuko and Azula fighting over turtle ducks as their father steps in to explain the rules that a fight, once begun, only ends when one wins and one loses.

Avatar: The Last Airbender season 2 episode 2 recap
Aang, Katara, and Sokka are in a small Earth Kingdom town trying to scrape together money and supplies for their refugee group. Blessed pilgrim status, it turns out, doesn't get you very far when people want actual currency. A stranger tips them off to Earth Rumble, an underground earthbending fighting tournament with a big prize purse, and they head over to watch and potentially enter.
The tournament's reigning champion is The Boulder, a theatrical earthbender who narrates his own fights in the third person. He's very entertaining. But the fighter who stops the episode cold is someone called the Blind Bandit, a seemingly unassuming girl who walks into the ring and dismantles The Boulder so efficiently it's almost funny. She just waits, feels where he's going through the vibrations in the ground, and redirects everything he throws at her. Aang immediately recognizes that he's the neutral jing in action that Bumi had told him about in the previous episode. And this is going to be his earthbending teacher.
The Blind Bandit is Toph Beifong, daughter of one of the wealthiest and most powerful families in the Earth Kingdom. The Beifongs invite Aang to dinner, as they're longtime benefactors of the Avatar, and Toph sits at the table pretending she has no idea who he is and that she definitely doesn't go to underground bending tournaments. Her parents treat her as completely fragile, constantly worrying about her soup being too hot and referring to her as their "little flower." It's clearly suffocating her, and you totally get it while watching.
After dinner, Toph and Aang have a conversation in the garden that's the quietest and best scene in the episode. She tells him about running away as a child and hiding in a cave, where she found badgermoles, blind like her, and learned to earthbend as a way of sensing the world. Everything vibrates, and the earth connects everything, and that's how she experiences reality. She has no interest in teaching Aang, but she talks to him anyway, and the audience can feel that she hasn't had many conversations like this one.
Meanwhile, Zuko ends up sheltering with a farming family of a teenage girl named Fei and her younger brother Peng after helping Peng at a checkpoint where corrupt Earth Kingdom soldiers were shaking down civilians. It's a kindness that lands Zuko in their home for the night, and Fei slowly draws out of him that he's looking for someone, though he won't say who. She tells him about losing her parents to the Fire Nation quietly. Zuko sits with that in a way that's uncomfortable for him and visible on his face. The episode cuts between this and flashbacks of young Zuko and Azula, their mother's warmth, and Ozai's coldness, the night their mother disappeared. We get the idea of what happened without the full picture yet.
When Azula and Ty Lee track Aang to the village, Azula finds Zuko and offers him the pardon. Ozai has lifted his banishment, she says, and she's been sent to bring him home. Zuko doesn't believe her or doesn't want to. They fight. Aang gets caught in the middle. Toph shows up and joins in, apparently having made up her mind about the teaching question. The fight is chaotic and ends messily, where Azula retreats, Iroh gets injured, and Zuko is left helping his uncle while Aang's group escapes.
The episode ends with Toph walking out to join them, telling Aang she'll teach him earthbending if it kills her. And the Beifong family, back at the manor, is hiring The Boulder to bring her home. Oops!

Avatar: The Last Airbender season 2 episode 2 review
Miya Cech's Toph works. That's the main thing to say. The character is one of the trickiest in the whole show to get right. She's abrasive and funny and unexpectedly tender underneath, and the temptation is to play up any one of those qualities at the expense of the others. Cech's performance here finds the balance. The garden scene with Aang is the proof where she's guarded and dismissive, and then she talks for two minutes about badgermoles.
The Beifong parents are a nice touch too. They love Toph in a way that's not right for who she actually is. Her mother pulling her away at the end, telling her she's too delicate for all that, and Toph saying quietly, "I'm not a flower; I'm a rock," are nicely written.
The Zuko material is strong again, and I love every scene with him in this season as well. The flashbacks are integrated perfectly, and the scene where Fei tells him about her parents dying is handled with restraint on both sides. What it does to Zuko having to sit there and receive that, knowing what he is and where he comes from, is written into his face. Dallas Liu continues to be the most consistently interesting performer in the show.
Azula's arrival is effective. There's something cold and almost bored about how she approaches the whole situation, from finding Zuko and offering the pardon to pivoting to the fight without much change in expression. The line about running her father's errands is "Conquer Omashu. Fetch his failson" is funny and a little sad at the same time.
The weakest thread is probably Sokka and Suki. There's a conversation about jing and positive energy that's meant to be about Sokka suppressing something that happened in the North, something he won't talk about, but it's too vague to land properly. I didn't feel like I understood what it was, only that the show wanted us to know he was carrying something.
The action in the Earth Rumble sequence is fun, and The Boulder is exactly the right amount of ridiculous. The final fight in the village is busy but readable, which is more than can be said for some of Season 1's bigger set pieces.
"A Fight, Once Begun" is a confident episode. It delivers on the promise of the first, introduces a major character properly, and moves several things forward without feeling rushed. The show is finding its feet.
