Okay, so the summary of Book 2 of LoK is going to be a bit shorter because I don't feel like looking for my notes.
I also never did a write up of Amon, which if a bit relevant. Honestly, I didn't technically change too much with him. Same basic backstory of his father being abusive....but the whole "I can bloodbend the goddamn city!" thing is thrown out. It's OP, ruins the uniqueness of the mythical connection to the moon, and doesn't make sense with Amon's debending abilities. Instead, Amon is just a regular crime lord that Aang took down. Tarrlok didn't show waterbending abilities until later (he's not great at waterbending) and their mom wasn't a bender, so he basically grew up in a bigot's home talking about how anyone who couldn't bend was shit. Noatak eventually comes under the influence of an evil spirit, who exasperbates his feelings of bitterness and resentment, and as Noatak gives in more to him, the more powerful he becomes. He is able to give Noatak the gift of debending in exchange for more influence, until they are both starters of their movement. So when Amon is defeated, it's not because he fell in water, it's because Korra forces the spirit out, reducing Noatak to just a man, much less fanatical, less charismatic, less everything. I should note this isn't an instanteous process (especially because Amon DID have connections to the Red Lotus in my version), but Amon's ultimate fate is to slowly be a voice of progress for non-bender rights and representation in republic city, working with the Avatar.
Anyway, So, Korra's defeated Amon, Asami's story was similar to hers in Season 1 in regards to her father, but she actually was working to bring down the triads as a costumed hero before, and she just joined Korra because she's the goddamn avatar. Mako and Bolin are not really up to romance shenanigans, but Mako at this point has a health admiration for Korra that edges a bit into romance, while Bolin is her personal fanboy/friend, and they basically are a Krew at this point. No romance between Asami and Mako. They, plus Tenzin, have all bonded together at some point and care about each other.
So, next step, Korra has to learn to access her avatar state (which she didn't in the first season). Asami took down the Triad bosses, but they still somehow have a functioning network. Asami has already sensed a shadow boss pulling the strings in season 1, and this season is about finding out who. Mako and Bolin have both taken to heroics via their adventure with Korra and THAT has incentivized them to find opportunity in fighting against crime, so both of them join the police task force as apprentices under Lin. Lin works with Korra and Asami often on Triad business, so it's a nice way to set everything up. But there are questions that linger on the Krew's mind. What was that spirit, and how did it get there? And what was the Red Lotus that Amon talked about?
Well, the story would be combining a lot of parts of season 2 and 3 and then making up a chunk of it by myself. The Krew would get a message that they must travel to Suyin's city. Korra is attacked by the Z-team, and while they fight them off temporarily, Tenzin recognizes them as the ones who assassinated Aang, which basically makes him think "oh shit, Korra can't stay here." They needed to go to Zaofu, for many reasons. 1. it's one of the safest places in the world, 2. it's set on a spiritual location that could be contusive to Korra's education (one of the many controversies that Suyin faced was building her city on/near a spiritual area that many thought should be preserved), 3. there is evidence to suggest that the Triad is bigger than Republic City itself, and Bolin and Mako (and Korra and Asami, by association) are tasked to follow a slim lead.
Once they get there, Suyin and Kuvira are both there to help them. Kuvira, as I said, is often going on her own missions that Suyin sends her off on, but for this, she was pulled back to help and protect the Avatar from the Red Lotus. Kuvira here is an interesting experiment because she's essentially the sixth ranger, trying to fit in to a group that has already solidified it's friendships with the known members already....even though she already knew Korra and had a real friendship with her, it wasn't the kind of that the Krew had. The Krew were close and open and warm and affectionate, while Korra and Kuvira's were close in their own way, but not explicitely so. It makese her feel like something of an outsider, like she is losing a friend. But throughout the season, she does try and bond to the rest of the Krew, especially to Korra who she values above all others. She also likes to spend time with Suyin, who she sees as a motherfigure.
Here is where we get the backstory of Kuvira. She was an orphan girl. She remembered that her parents were rich and wealthy people, but not much else. There was an attack by some kinds of Terrorists in the earth kingdom. Suyin found her, and took her in. She raised Kuvira closely, but Kuvira never knew....stability. Sometimes she felt like she was her full fledged daughter, sometimes like a beloved friend rather than family, and she couldn't ever tell if that was a real feeling with Suyin or if it was just her insecurity or even just memories that she was, in fact, an adopted orphan. She was certainly raised differently than the rest of the family. But then again, everyone in that family took to something unique. Was it so different that Kuvira took to combat and military from a young age while Opal took to painting, Bataar Jr. to engineering, and so on? It's a question that plagued her mind. Something she shared with Korra, who reassured her that Suyin loved her like a daughter.
The Red Lotus were coming, and Korra needed to tap into her Avatar Spirit. It took a while, but Tenzin finally worked up the courage to help his student get to where she needed to be...and to do that, they needed to travel to the spirit world to seek help. Tenzin, if you don't remember, had a bad experience doing this. It's why he prefers dry, hard aspects of Airbending like simple meditation or studying the histories and so on. But Korra needed to connect to her past lives, so into the spirit realm she went. There, they would learn about how to Spirit bend. I wanted to make sure that Korra learned something new every season, like Aang did in TLA, and since she has all the elements down, here we can discover more about how the spirit world works, so this is my new interpretation. In the spirit world, you don't bend fire, or earth, or any physical property, because they don't materially exist. In the spirit realm, you bend the actual thing that powers those physical elements. So if is drive and motivation that create fire when firebending, in the spirit realm, you bend drive and motivation itself. This, we discover, is what Aang did to Ozai in the TLA finale. Physically, Ozai is fine, but he literally took away his drive, which means not only could he not focus enough to create fire, but he could barely motivate himself to move his limbs. I think this is a cool idea, a kind of bending that warps not physical properties, but who you are as a person. I always found this idea to be scary and definitely worse than killing a person. In this, we have Korra fight some kind of enemy, maybe spiritual Zaheer or else maybe another spirit. In any case, here they learn more about what is going on, who the Red Lotus are, what the goals are, etc.
The Red Lotus want to indeed take the Avatar out of this world, and spirits are creatures who are manifested by the influences that occur in the real world. The spirit that attached itself to Noatak was called Amon, he was the Spirit of the Hundred Years War. Not long after the War ended, it tried to revive it, but was stopped by the avatar. It's old now, and the world's changed so much that it is impossible to make it work anymore. A new spirit was born from it which was the spirit of the Red Lotus, who has the same antagonism toward the avatar, but adjusted for the new world that can no longer see the revival of the old war. But Amon, the Spirit of the Old War, with no chance of being returned to his former glory, he just wants to kill himself and he can only do that by taking away bending, which is how he was able to drive Amon's rage further than it would have gone on it's own. But it's successor, the Spirit of Destruction and Rebirth of the World (in this case, meaning society) would live on, because the Red Lotus was thriving. It didn't want to revive the old war, but it wanted to shape the new world, and it was omnipresent, operating in every corner where Red Lotus members operated. But the bigger spirits are, the harder it is for them to enter into the world...but if they can, they would be able to end the avatar, and from there a new age would begin as people would need a new world leader that brings the four nations together. The spirit gives them flashes of it's plans. Destruction of the Earth Kingdom and the rise of Zaofu. In the symbolic birth of the new world order, it would there would be an opening, and it could enter the real world in a more meaningful way than it could with Amon. Korra ends the old spirit using spirit bending. When she takes away his last remnant of drive to continue his war, even against bending itself, it disappears.
Anyway, meanwhile, Asami, Bolin, Mako and Kuvira have been investigating the trail that Suyin gave them, and they kept finding more and more evidence of a criminal empire network system. Messengers with coded messages, supplies that would ship and supply the Triad with weapons and authority figures if necessary....it was well hidden, but one discovery lead to another, and the cover up just kept getting bigger, and bigger, and bigger... (I know this sounds like it's vague, but I'd be more detailed on an episode by episode basis. We'd have plenty of time. A lot of season 2 of TLA was spent just getting to Ba Sing Se, while the Krew would spend nearly all their time in Zaofu, so plenty of time for various kinds of exploration. Asami and the rest still get their own various miniarcs, it's just, i'm trying to keep this as short as I can).
Eventually, Asami and the rest had to realize that Suyin's entire city has been taken over by some kind of shadow government. Whatever mysterious master the Triads had in Republic City, their presence was stronger here. Kuvira brought this to Suyin, begging her that she needed to know what to do, now that her entire home has been revealed to be not just under siege but already defeated from the inside. Suyin tried to think of what to do...but there was nothing for it and she revealed herself to be the actual Triad shadow master. Her criminal empire has been spread throughout of the Earth Kingdom, but Zaofu was her base of operations, the distance from which she controlled the entire nation...or tried to, since the real Earth Kingdom has fought her.
Suyin captures the Krew, and Kuvira gets her own cell. Suyin thinks she might still turn her. After all, she raised Kuvira as a daughter. She revealed to her. She wasn't just some ordinary orphan. She was the princess heir to the Earth Kingdom itself. The truly rightful queen, as the queen that ruled now was a despot. How much better she would be sitting on the throne, once that awful woman was removed from power. She could bring peace and prosperity to a nation that she KNEW was corrupt and evil, and instill the values taht Suyin raised her with. (I'm trying to imagine Suyin pretty similar, atleast superficially, to how she was in the show. A progressive, polite, human rights advocating kind of leader. Suyin justified what she did under the fact that she believes that crime and corruption under her control is better than out of control. I want to make a point that she might be right. Better is not "good", but I like to think she might have a small point under everything else). Kuvira is left to stew that over. Asami and Mako and Bolin spit in her face about it when she goes to give them the same spiel. They personally experienced her 'controlled' corruption. They're not impressed. Kuvira, not wanting to believe her mother has truly become evil, tentatively says that she agrees. She's still unsure if she truly believes, but she wants to. Asami, Mako and Bolin all feel betrayed by her.
Korra eventually returns. She's been captured by Zaheer and his team. She panics, but there's little she can do. Suyin demands that the Red Lotus uphold their end, and they say they do. Zaheer uses his spirit thing to send messages to get the Earth Kingdom assassination plot started. Kuvira in the meantime struggles, as Korra pleas and argues with her beloved friend about what she's doing. Kuvira wavers....eventually giving Korra a chance to escape, but unsure where that leaves her with Suyin and her family. From there, Korra and company have to defeat the Z-team, which is very difficult as not only are they all extremely skilled benders, but also have reinforcements coming. Korra, however, can go into the avatar state now....which of course is her when she's at her greatest risk. Zaheer beats her down, severing her connection to her lives. To his goals, he wanted to eliminate the Avatar....and he, for all purposes, did. Korra was reduced to just being a bender now. A bender of all 4 elements, sure, but that was hardly important when she was not able to bring force the hurricane force of a thousand lifetimes. He leaves her, seeing no point in harming her further.
In the moment of weakness and identity crisis, Kuvira is the first one she sees and they have a major falling out over her actions, and the Krew have no desire to help her after what they see as an ultimate betrayal. "You were never one of us", they say something to the affect of, which is the worst thing you can say to Kuvira. With the reveal of Suyin, her family also kind of falls apart. Kuvira was always closer to Suyin, more than anyone else, so Opal, Bataar Sr., etc....especially given that Kuvira sided with Suyin, they doubt her. They don't reject her, but they doubt her, and that's more than enough to send Kuvira running. Only Bataar Jr. followed after her.
She somehow ends up at the spirital center of the city...where the new destruction spirit is awaiting a vessel that has a desire to see a new world...one where she will fit in, because she will make it.
Korra and company now are in hiding. Republic City is not safe, though Tenzin needs to go to make sure his family is okay, and SOMEONE has to break the news to Lin so they can start fighting back. Korra lost her connection to her past lives, but as her friends gathered around her, she remembered what she felt when she defeated Amon. It wasn't her bending that made her the avatar, it was her spirit. She was connected to all 4 elements, and all 4 nations. Being the avatar meant you didn't give up, so she would find a way to root out the Red Lotus. She would save the Earth Kingdom.