Technology has radically changed the world of Legend of Korra, giving its people the wonders of trains, cars, and radios. But with Kuvira moving on the Earth Empire's final holdout, we see how technology also has the potential to make warfare in the Avatar world more devastating. How can the Avatar match the advancements in weaponry?
Well, we wanted a problem that Korra couldn't punch her way out of, didn't we? Kuvira's army is marching on Zaofu just as Korra returns to action. Kuvira and Baatar Jr. saved their hometown for last, and once it joins their empire, the entire Earth nation will be united. But that means convincing Su to give up and join their cause. So they send in the big guns: Bolin.
Even in her power madness, Kuvira recognizes the value of Bolin. He's the warm and friendly face of unification, and he's a true believer—at least until he realizes what unification truly means. What's particularly interesting about this episode (aside from the implications of the nuclear Spirit bomb) is that we see how god intentions sent Kuvira down this path. President Raiko and Tenzin initially approached Su to fill the power vacuum in Ba Sing Se, but Su wasn't interested in being a conqueror. Kuvira recognized that something had to be done to stabilize the Earth kingdom, and her initial plan was to make Ba Sing Se more like Zaofu. But power has corrupted Kuvira, and she believes that she should manage every aspect of the kingdom—including the work people do and the political ideologies they can espouse. She doesn't just want a stable nation; she wants a watch made up of human clockwork.
And as her power has grown, she's willing to justify and means to reach her ends. Varrick has been hard at work on his Spirit nuclear power project (and quite perfectly, he named the energy units after himself and the weight units after Zhu Li), but ends up blowing out the back of Kuvira's train when the experiment doesn't go quite as planned. Kuvira is delighted by the potential of this new weapon (at least, I assume she's delighted; Kuvira isn't terribly emotive these days), but Varrick is so horrified by the devastating possibilities that he's ready to abandon his usually mercenary ways and shut down the project entirely. It's finally happened: Varrick has developed a conscience.
That's why Varrick, Bolin, and Zhu Li end up fleeing Kuvira's camp in a trio of mecha suits. But Kuvira isn't about to let the information about this weapon slip away. The three are captured and dragged back to Kuvira—and Zhu Li throws herself upon Kuvira's mercy.
Hmm, so has Varrick's abuse and neglect finally driven Zhu Li away? Or is she acting as a double agent? And if it's the latter, is she doing this in hopes of finally winning Varrick's approval? Because if so, you've got issues, lady, but we're looking forward to seeing what you pull off.
"Why did we go through all that trouble to save you if you're not going to beat someone up?" It's Meelo who says this to Korra, but Su is the one who treats the Avatar as a living weapon. She wasn't willing to march into Ba Sing Se, but Su is ready to resort to violence to demolish Kuvira's army and remove her from power. But Korra's been through too much personal growth for that. She tries to reason with Kuvira, but Kuvira out-reasons her, convincing Korra to request Su's surrender. But Su isn't interested in diplomacy. She's ready to take down Kuvira even if it means going after her herself.
I have a queasy feeling about how this could all turn out. I could see Kuvira attempting to deploy the Spirit bomb to destroy Zaofu—both as a show of power to the other nations and to make Zaofu's surrender moot. And I could see Korra sacrificing not just herself, but also the Avatar line in order to save the city. With technology outpacing bending, the world needs places like Zaofu more than it needs an Avatar.
Then there's Asami and her father. Seeing Hiroshi in prison is a striking reminder of how much the world has already changed since Book One. Not only did Amon's rebellion fail, there's actually more bending and mysticism in the world. Hiroshi has changed too. Gone is the proud man full of rage at benders. Instead, we have a man who has been humbled and realizes that his hatred destroyed the one thing he truly valued: his relationship with his daughter. If Hiroshi has reformed, does that mean Kuvira isn't beyond hope?