Why The Villain Of Avatar: The Last Airbender Wasn't Actually The Fire Lord
As the opening of Avatar: The Last Airbender reminds us, the balance of the world and the elements (water, earth, fire, and air) was disrupted when Firebenders took control and the previous era's Avatar — later revealed to be Roku — disappeared. As the new Avatar, it's Aang's job to restore that balance by mastering all four elements and defeating the head of the Fire Nation: Fire Lord Ozai. The task seems even more insurmountable when Roku's spirit informs Aang that he must topple Ozai before the arrival of Sozin's Comet, which will grant all Firebenders unimaginable power.
Ozai thus generates a looming dread, more a pure incarnation of evil than a true villain. Indeed, Team Avatar encounters far more devious threats, not the least of which comes in the form of the Grand Secretariat of Ba Sing Se: Long Feng.
Long Feng's reach extends over the Earth Kingdom
Armed with crucial information that could bring the long war with the Fire Nation to an end, Team Avatar seeks an audience with Earth King Kuei in order to get the Earth Kingdom to take an active role in the war, but is instead brought to speak with Long Feng. By leveraging political power, intelligence, and espionage, Long Feng and his Dai Li agents — secret police, essentially — have for years kept all news of the conflict from penetrating the city walls.
Everyone, then, from street vendors to the king himself, is blind to the perils the Fire Nation presents, forming what Long Feng calls "a peaceful, orderly utopia." In his eyes, the only way to maintain said utopia and prevent universal panic is to quash all talk of the war before it spreads, even if it means brainwashing those who know the truth. When Aang declares he'll tell the citizens of Ba Sing Se anyway, Long Feng puts him and the others under watch and threatens expulsion, which would heavily impede the search for Aang's flying bison Appa, who was missing at the time.
Long Feng invites you to Lake Laogai
We later learn it was Long Feng himself who captured Appa, using a call whistle much like Aang's and a deft display of earthbending. Like all his other victims, Long Feng had the flying bison sent to Lake Laogai, a prison for those who threaten the "peace," as well as a training facility for both the Dai Li and the Joo Dees. Team Avatar eventually locates the lake with the help of Jet, a former enemy who himself was taken below the water and brainwashed by the Dai Li.
Long Feng and his lackeys are there to confront them, of course, ambushing from the shadows — because even in combat situations, the Grand Secretariat prefers a tactical, thought-out approach. For encroaching on Lake Laogai, he labels the members of Team Avatar "enemies of the state." Once the Dai Li are defeated, Long Feng — in keeping with his manipulative ways — turns Jet against Aang with another fit of brainwashing, only to grievously wound Jet himself before backing off.
It is only later, on the shores of Lake Laogai, that Long Feng is finally bested by none other than Appa, who ironically tosses the slimy politician back into the lake. And though Long Feng later attempts to eject Team Avatar from the throne room to stop Earth King Kuei from hearing the truth, Appa's bite mark is used to convince the monarch to at least hear Team Avatar out.
Long Feng loses control
Aang and the gang bring Kuei to Lake Laogai to prove his "most loyal attendant," as Long Feng once referred to himself, disloyal. All evidence of the underwater facility, however, is found destroyed — undoubtedly the work of the Dai Li under Long Feng's direction. But there's more evidence: The Fire Nation drill previously used in an invasion attempt. No excuse can cover that up, and Kuei has Long Feng arrested.
Even imprisoned, though, the man still has a few tricks up his sleeve. Having learned of Azula's search for Aang through Dai Li spies, he strikes a deal with her: Use the Earth King's trust in her (since she's disguised as a Kyoshi Warrior) to keep the monarch off balance, and he'll get her the Avatar. Working behind the curtain is standard practice for Long Feng, as attested by his arrogant smile.
Yet Long Feng soon finds his confidence misplaced. After release from incarceration, he orders the Dai Li to arrest the Fire Nation princess and wrest control back, but their loyalties have shifted, and Azula both literally and symbolically takes the Earth Kingdom throne. All he can do is admit defeat, and so he does.
Following Long Feng's twists and turns was as engaging for the audience as it was enraging for Team Avatar. The enmity he presented was subtle, careful, and planned — much the opposite of Ozai's power-flaunting ways — making him truly an Avatar: The Last Airbender villain for the history books.