Fire Lord Zuko is making a return: http://www.theotakukid.com/wp-content/uploads/2014/06/The-Legend-of-Korra-Book-3.jpg
Book One of Korra was set up as a sort of stand-alone 12 episode mini-series that then got picked up for a further 3 seasons to bring the episode count up to 52 in total. I could be thus assumed that Book Two would set up the other two Books that would conclude the story of Korra, just like how Aang had his three books. Book Two however had its own antagonist who was beaten and the world was returned to a state of balance so should this Book been seen as a standalone series too? In short, no. I would argue that Book Two was brilliantly played out but in the end was just a set up series for the main story of Korra's avatarship to unfold.
The meme a co-creator of Korra (Bryan Konietzko) made to announce more books as a series beyond season 1: http://bryankonietzko.tumblr.com/post/27078349740/im-sure-this-meme-is-dead-by-now-but-it-still
Many would argue though that Unalaq was an enemy worthy of his own series and this Book was more than just set up for something else. With Unalaq and his attempt to become the "Dark Avatar" is where the writers got it right in being able to show this as something more than just a prologue. Everything about Unalaq and Vaatu was cosmic: Korra had to reconnect with the first Avatar to just learn about Unalaq's plan; Unalaq vs Korra was going to invlove, quite literally, the spirits of good and evil, or rather "light and dark"; and of course Unalaq's plan could only happen during the Harmonic Converge (where the planets align), which only happens every 10,000 years. How could an enemy that could only be created with a ceremony so cosmic be just a mere introduction to the main story? This is what the writers did right with it. They were able to create an antagonist that would seem like a main villain, due to the epic scale of his powers, but is just a tool for set-up.
Early concept of Unavaatu: http://bryankonietzko.tumblr.com/image/67728323264
The next two Books in the Korra series (Book Three: Change and Book Four) surround the events that happen in consquence of Korra leaving the spirit portal open. Obviously the writers wanted to do something big and drastic to the world, namely letting the spirits into the world (and having watched the first three episodes give many new people, including the new antagonist airbending powers). How could they do this? Well obviously Harmonic Convergence was conceived of as a way for Korra to open the portals and change the world in a good way for new ideas and new storylines to develop. So the writers had to answer why were the portals opened. They could not do it out of Korra's storyline, so they had to make her do it. Thus they had to make a reason for Korra to open the portals and keep them open. Thus Unalaq was conceived of as someone who could trick Korra into opening the portals and as the person who presented the arguments for keeping the portals open (saying how the humans had lost touch with the spirits). Other factors (such as seeing Bumi's friendship with the dragonfly bunny spirit) also convinced her to keep it open, but Unalaq was the driving force. In other words Unalaq was an enemy not for a great story but just to get Korra to open the portals and leave them that way so that storylines could be created for the next two books.
Fanart of human forms of Raava and Vaatu with Korra and Wan: http://th03.deviantart.net/fs70/PRE/i/2013/310/d/9/harmonic_convergence_by_little_mongolian-d6syksz.png
I would further argue this because Unalaq and Vaatu as enemies were very cliched. I mean he was set up very early and rather obviously as the one who would be the main antagonist. The writers tried to do what they did with Amon in making his cause seem worthy (this time arguing for spirituality instead or arrogance towards the spirits or spirituality vs secularism) but then his cause becomes just about power. Amon's cause was one many could get behind and this made the first series great as I said before: http://animevigil.blogspot.kr/2013/09/amon-equalist-legend-of-korra-season-1.html. However, Unalaq, as it eventually turns out, just wants power. He was willing to sacrefice his son in order to open the second portal and as his children admit at the end "he had beomce a deplorable man". He fuses with the manifestation of evil, the spirit of darkness Vaatu. In doing this he becomes the "Dark Avatar". I am sorry but you don't get more comic-book cliched than that. Basically because Unalaq and Vaatu, by the end of series, had become so cliched that the story was nowhere as compelling as the first Book I would say this Book was made to introduce the next two, hopefully more morally ambiguous and thus interesting, seasons.
Fanart of Korra with the spirit of Raava: http://i1.ytimg.com/vi/mBmUCe6Q2Zk/maxresdefault.jpg
Furthermore, Unalaq was not really set up as an enemy with a backstory. For Amon we had the backstory explained to us by Tarrlok who told us about Amon's childhood, connection to bloodbending and the reasons behind his move to take other's bending away. For Unalaq, yes, we are told of how he got his brother banished (by the corrupted judge) and for Vaatu we are told of his goals and ambitions through Wan's story, but it still leaves me with unanswered questions. We are told of how Amon got his bloodbending ability, but how did Unalaq get his connection with the spirits and where did he learn how to control them? I suppose we can assume by studying very hard or just naturally etc. But the main question for me is: how did Unalaq find out about Vaatu, Harmonic Convergence and when did he decide he wanted to fuse with Vaatu? I mean sure Tenzin knew about the "Tree of Time" but if he had any idea of Hamonic Convergence surely he would not have left Korra so quickly for his family vacation. I suppose again we could say his studies told him about Vaatu and Raava, but again why does no one else know. I think Korra was right at hinting Unalaq was jealous of his brother when said "it must have killed you to find out your brother was the father of the Avatar". This could be a motivation for fusing with Vaatu, because of his jealousy for his niece. Did Unalaq go into the spirit world before? Wan Shi Tong knew him, maybe he studied in the library and found out everything, then when he found out his brother's daughter was the Avatar he decided to become the "Dark Avatar" as he already knew about the nature of the Avatar, Raava and Vaatu from his studies with Wan Shi Tong. This is all speculation and because I can only guess at this backstory, it makes me think Unalaq was not properly thought out as say Amon was and is just a means to creating a new set of storylines in a new world of the Avatar.
Fanart of Korra doing her spirit thing: http://artipelago.deviantart.com/art/Korra-Spirit-407380348 This artist has many more works on the Legend of Korra, check it out.
I mean the only way Korra found out about everything to do with he nature of the Avatar, Raava and Vaatu was through her connection to Wan, something Unalaq did not have. In fact the story of Wan is crucial to this argument. Although it says how Wan became the Avatar and why Unalaq must be stopped it does so in a rather long narrative way. It goes into who Wan was before the Avatar (in order to show Korra she has her on spirit and is not defined by Raava) and it tells the story of Raava vs Vaatu (to show why Unalaq must be stopped due to the nature of Vaatu). However, the story as tells about Harmonic Convergence (yes necessary for Vaatu and Unalaq's plans) but just as necessary for setting up the next seasons as consquences of a new world brought about by Korra opening the portals. In addition the story of Wan also showed how spirits and humans interacted and what they thought of each other. How spirits thought humans were destruction and selfcentred and how humans thought spirited were to be feared because of their mystical powers. It even showed a few scenes of spirits and humans fighting to bad results (a plot point for the next two seasons??). The reason Wan became the Avatar was because he was different to all other humans. The story also shows why exactly he closed the portals, which of course sets up how when Korra leaves the portals open she will change the world. Thus, the two epsiode story of Wan, as artistically appealing and interesting in terms of the overall world as it was, can be seen as a story about the Harmonic Convergence and the relationship of humans and spirits, just as much as it is about Vaatu, Raava and the Avatar. The story of Wan sets up how the world will change at the end, which is necessary for this to be a set up season, just as much as it was for driving the antagonist characterisations forward. It is interesting to note how different Wan's drawn out fusion with Raava was compared to Unalaq's comparatively simple fusion with Vaatu, as it shows there is a little bit of inconsistency given to this aspect of the tale.
Wicked fanart of Avatar Wan: http://www.deviantart.com/art/Avatar-Wan-411857563
Lastly, why was the Harmonic Convergence needed? Having watched the first three episodes it shows that it has given Korra something to fix in Republic City, which when she cannot she is driven out by the president. Second it gives the main antagonist, although with others, a power he could not possibly have before Harmonic Convergence. The antagonist of the new series, the leader of a group of four escaping capatives (held by the White Lotus in secret prisons restricting their bending) was given the power to bend air. The reason behind it is Harmonic Convergence presumably releasing energy to balance the four nations but nothing has really yet been revealed. This also gives Korra a new task, outside of Republic City, to find the new airbenders, and restore the Air-Nomad culture at the various temples. This to me is much more interesting than the take down the purely evil guy that was in the second season. Two weeks on from the Harmonic Convergence and the reasons for having it as a set up to these new problems looks interesting.
Fanart of Korra vs a dark spirit: http://solkorra.deviantart.com/art/Korra-vs-Evil-Spirit-South-Pole-Batlle-378632449 This artist also has more Korra artwork.
As an end note the second season left two interesting plot pieces open, which the first season did not. First Varrick was able to escape prison with Zhu Li (after "doing the thing") and was not seen from again. Could he return? Also, like Amon, Unalaq dies in the end. Although Amon had no family and no place of power outside his rebel group, Unalaq was chief of the Northern Water. Yes, the South was given a Chief in Korra's father, Tarrlok, the North has been left without one. In the trailer fo the third season we saw Desna and Eska waterbending, along with a host of others using their powers, such as someone who appeared to be a highstanding citizen of the Earth Kingdom and a firebending King Zuko (recognisable by his scar). Will their be a war? Who will start it? As we hav seen from The Legend of Korra, the Fire Nation, is not the only nation capable of invasion. Having watched the first three episodes of the new season it definitely hints that the Earth Queen is one to watch, in terms of both riches (like Varrick) and invasion, although it seems more likely she will invade Republic City to regain former Earth Kingdom territory (and maybe more).
Season 3 Big story is Korra must rebuild the Air nomads and their temples: http://www.awn.com/sites/default/files/styles/original/public/image/attached/1016847-korra_1.jpg?itok=GcjkhfuU
In conclusion, yes the series was great, in some areas. It shows a great relationship between Tenzin and his siblings Kya and Bumi. Likewise the relationship between Mako, Asami, Korra and Bolin, especially the love triangle it created, was interesting. However, as the season went on it started to pale in comparison to its predecessor and now that season 3 has started it really just feels like a set-up story rather than something that was as clean and well rounded as season 1. First, the enemies came off feeling too cliched after Amon, who is for me one of the best antagonists I have ever seen on the screen, big or small. Second, the plot, in terms of Unalaq backstory and motivations were too unclear and not really specificed other than "he just wants power". Third, Third, the story of Wan (the first avatar) was not just set up for Raava vs Vaatu, it was set up for the Harmonic Convergence and the relationship of spirits and humans, with which the writers could preface the next two series. So due to this I felt that the second season of Korra was well done but due to failings in areas is just a set up for stories that I hope are more interesting and less cliched and obvious as light vs dark, especially as the leader of those four capatives called their path "a righteous one".
The dynamic family issues of Tenzin and his siblings was a highlight for Book 2 and it looks to continue with Bumi turning out to be an Airbender. http://metaboo.tumblr.com/ This artist also has several very good pieces on Korra Season 3.
