Avatar Aang deconstructs the Kid Hero. Each Avatar is supposed to learn of their identity at the age of sixteen, which is the age of majority in the World of Avatar. However, when the leaders of the Air Nomads sensed that a war was brewing, they made the decision to reveal Aang as the Avatar four years early so he could finish mastering his airbending and start mastering the other three elements to nip the threat in the bud. This decision might have made things even worse for everybody involved at the time because it forced a huge responsibility onto Aang that the 12-year-old wasn't ready for, and alienated him from his pre-series friends who were themselves too young to know how to treat him post-revelation. After overhearing he was to be separated from Gyatso, his guardian and the only one left who treated Aang as the kid he was and as an actual person, he ran away, and then got trapped in a storm that forced the Avatar State to freeze Aang and Appa inside an iceberg for a hundred years in order to save both of their lives. He subsequently blamed himself for the genocide of his people and the subsequent century of war because he wasn't there, even after he's told he would've been too inexperienced to make a difference back then and that his running away then is probably the only reason there's hope for the surviving world now. His childish personality and cheerfulness is sometimes an act to try avoiding the burdens placed on him which proves to be a problem several times when he has to face a problem head on to solve it (like learning Earth-bending or spending almost the whole series avoiding the problem his morals might conflict with what he'll have to do to actually defeat the Big Bad).
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Team Avatar sans Iroh deconstruct Free-Range Children; the reason why a bunch of preteen and teenaged kids can travel around the world all by themselves is because all of their parents are either dead, abusive, and/or busy fighting in the war. They all are also Child Soldiers, whether or not they have Elemental Powers, because the series takes place during a century-long global war and they have to know how to fight to survive the hundreds of combat situations they're forced into. They also have to know how to fight since their ultimate goal is to end the Hundred-Year War, and because Fire Lord Ozai has made it clear he won't end his reign of terror on the world they have no choice but to use violence to take him down.
Roku's portrayal in The Promise deconstructs the Spirit Advisor trope. Roku is well-intentioned in his advice to Aang to strike down Zuko before his withdrawal of support for the Harmony Restoration Movement triggers another world war. However, he is (A) poorly equipped to handle the increasingly complex issues of the modern world, and (B) projecting his own regrets over his failure to kill Sozin onto a radically different situation, driving Aang to cut ties with him for a year. When they reconcile in The Rift, Roku acknowledges his own failures and states that he and his predecessors can only give advice from their own perspectives; Aang must balance the past and present, much as he must be the balance between humanity and the spirit world.
For the former two tropes, as stated above, most Avatars discover their status when they’re sixteen years old when the spiritual leaders of whatever nation they belong to tell them. In Korra's backstory, she discovers she's the Avatar for herself when she's four years old because she was able to not only bend her native element of water, but fire and earth without any proper training. She never got a chance to grow up emotionally due to spending her whole life pre-series inside a compound training to be a hero and responded poorly when first faced with genuine adversity. It also caused the lack of a self separate from being the Avatar because for as long as Korra could remember, she has always been destined to be the Avatar. This ends up resulting in Korra tying her self-worth to the occupation, so she always goes through an identity crisis whenever that status is threatened. A major part of her Character Development is learning how to love and accept herself beyond her identity and expectations of the Avatar.
Asami Sato deconstructs the Mad Scientist's Beautiful Daughter and Romantic Runner-Up. In the former's case, being vehemently and actively against her father still makes her guilty by association whether it's being arrested by Tarrlok for being his daughter or Future Industries having a tainted reputation from her father's actions, requiring years of effort to restore its good name and reputation all by herself. In the latter's case, being repeatedly ignored and disrespected by her boyfriend adds salt to the wound of the former to the extent of a rebound out of loneliness and desperation that's both embarrassing and leaves her jilted again. It's only by time and effort, ironically with her former romantic rival, that she catches a break.
Mako deconstructs the usual Pretty Boy lead, especially in a Wish-Fulfillment-loaded Betty and VeronicaLove Triangle. In Book 1, he's introduced as both handsome and competent in deftly taking down an entire team by himself and spends most of the season being fawned over by two attractive yet contrasting women and ultimately ends up with the heroine with whom he's had a purely Belligerent Sexual Tension-type dynamic. It's not until Book 2 when the deconstruction hits that he and Korra don't really work well together, and that same dynamic leads to him breaking up with Korra, rebounding to Asami then back with Korra under confused circumstances; this ultimately ends with him single, embarrassed, and looking like a jerk to most of the cast.
Bolin deconstructs the usual comic relief Idiot Hero. Contrary to Mako, being shielded from a Crapsack World not only leaves him feeling insecure in the presence of his older brother, but also immature and Super Gullible that makes him a sucker for any sweet-talking villain. This eventually stops being cute and gets him brutally reprimanded when he joins Kuvira, the Arc Villain of Book 4, because he honestly believes she's trying to restore the Earth Kingdom even after evidence of her dictatorial intentions start to show. This leads him to actively work to redeem himself and finally grow up after he finally realizes he's on the wrong side and defects from Kuvira.
Tenzin deconstructs the Old Master trope. Everything about his appearance and introduction in the series set him up as Korra's wise mentor; he looks almost exactly like an older version of Aang, has the tattoos, maintains an Air Nomad lifestyle complete with monk robes, and is the only living master of the only element that Korra has yet to get a hang of. He is extremely dedicated to Air Nation culture and the usual Old Master virtues of patience, careful study, caution etc. However, it turns out that he is in WAY over his head, having to come to terms with realising that he is not the wise master he desperately wants to be, has made many mistakes in raising Korra to be the Avatar, and is suffering a lot of baggage from the weight of his father's, and the entire Air Nation's, legacy on his shoulders that cause him to make several bad decisions. His daughter, and later his brother, have a stronger connection to the spirits than he ever will, a fact that causes him great insecurity. He eventually has to come to terms with the fact that he will never be like his father and must allow the Air Nation to grow into a new entity, not just a repeat of the old one, as well as let go of his protective nature over his children.
Baatar Jr. deconstructs Generation Xerox. He debuted in "The Metal Clan" just like the rest of his immediate family (and fiancé,) but whereas his siblings have Meaningful Names and Establishing Character Moments not only is he introduced simply as a Satellite Character to his father, only referred to as "my oldest" by Suyin, but he doesn't even talk as he's AWOL to the fight between Lin and Su in "Old Wounds" despite everyone else in the family being there and generally seems the absolute least like Toph overall. Turns out, he's had a chip on his shoulder all along exactly because he's seen as a mere clone of his father, to the point where he hates being called Junior, and part of the reason why he joined and eventually got engaged to Kuvira is because she allows him be his own man. He's practically a background extra raging against the author for being so unremarkable.
Jianzhu deconstructs The Atoner, Evil Mentor and Well-Intentioned Extremist. Blaming himself for Avatar Kuruk's decadence and negligence, in the belief that he failed to be a good enough influence on his friend, he becomes obsessed with mentoring the next Avatar into a worthier successor. The result is that he quickly and mistakenly identifies Yun as the Avatar by assuming a sheer coincidence to be a Reincarnation-Identifying Trait, goes into Sadist Teacher territory when Yun naturally has trouble firebending, is willing to kill people who try and get between him and being the Avatar's mentor, and ditches Yun without a second thought when he finally discovers that he isn't the Avatar. All these extreme actions alienate him from friends and potential allies that witness or find out about them; Hei-Ran makes clear to Kyoshi that she would kill Jianzhu without hesitation once she learns the full extent of his crimes, and Kyoshi herself escapes Jianzhu's estate and wants nothing more than to see him dead after he murders her adoptive father and leaves a close friend of hers to die as part of the above actions. As for Yun, Jianzhu ends up with very just cause to regret his actions; after Yun survives being abandoned to a monstrous spirit, his abandonment by Jianzhu and his learning that he was never the Avatar help cause him to Face-Heel Turn into an Omnicidal Maniac.
Yun deconstructs The Poorly Chosen One. Being wrongly identified as the Avatar, he's put through pointless Training from Hell by Jianzhu in order to awaken bending abilities he naturally has no hope of using, and Jianzhu later has no qualms with abandoning him once he learns the truth. Yun also takes the role very seriously, genuinely wanting to help the people of the world and making being the Avatar a key part of his identity; him learning beyond doubt that it was all a lie sends him into a Heroic BSoD at perhaps the worst possible time, and becomes a massive negative influence on his life; the second book has him planning to murder everyone who wrongly thought him to be the Avatar - on the basis that they "lied" to him about it - and it's also implied that he's acting out of resentment towards Kyoshi for stealing his destiny. Finally, when Kyoshi reveals herself to be the true Avatar, a lot of the Earth Kingdom nobility are not happy about her suddenly replacing Yun, and it's also suggested that a lot of deals and agreements Yun brokered as the Avatar will now be considered null and void.
