Disclaimer: I don't own Avatar. If I did, all female benders would be wearing tiny miniskirts. I kid, lol.but imagine the possibilities...
The mask represented a part of Zuko that he could only dream of. It gave him the freedom to do what he pleased, as long as he wasn't caught. The blue painted craft gave him a new face as a reward for finding it, and giving it a home.
Yes, the mask enjoyed its host and feasted upon the agony and pain of the banished prince.
Zuko knew of his entrapment to the mask and allowed it. The mask was like a parasite, he knew this. However, he stubbornly placed the idea unto the back of his head. He didn't want his conscience eating him from the inside; it served him no harm. What mask wasn't created to hide an identity? Or conceal a truth?
By day, Zuko lived his life with restrictions (banished from the fire nation, and continuing his search for the Avatar) but by night, he broke free of his restrictions and became The Blue Spirit. (He hated how mediocre his fire bending seemed, but disclosed the fact by using twin-bladed swords as his fire bending skills' own mask)
The fire nation uniform he wore during his exile represented the illusion of what he was before (Zuko, son of Ursa and Fire lord Ozai. He was the Prince of the fire nation, and heir to the throne). The mask represented who he was now, and although it served as a purpose for Zuko to live a lie, it was the only truth (he believed) he could hold on to; he became a spirit that wandered and sought no home or company. Like a ghost, it came and went as it pleased.
The transition from banished Prince to free spirit was stressful. He was living two lives, and feared his own mental demise. He only used the mask once to rescue the Avatar from Zhao's clutches, (He didn't do it to save him, he did it to save himself) but it kept calling him, begging him for more adventures. He was losing himself to it, and he could feel it.
When his sister appeared before him and his Uncle later on, he was branded the ultimate truth. His father didn't want him back, and everything Azula told him the previous day about how his father wanted him back home was a lie. ("Azula always lies, Azula always lies...") That truth burned more than his scar, the heat and pain rejuvenated by his younger sister's words. He fell that day, and like usual when he did fall, his uncle came to his rescue.
They ran away, ran as fast as they could until they found a remote area safe from harm. With a nod, Zuko unsheathed the dagger that was given to him as a gift (his uncle gave it to him), and hovered the blade against the hairs of his top ponytail. (Three, two, one...) then, with a single swift the blade grazed through the hair and his top ponytail was no more. ("Am I finally free from what I have wanted to become?"). He gave his uncle the dagger, but paid no attention to him grazing his top-knot and throwing it in the lake. Zuko glanced down at his own ponytail, unable to speak or describe his own feelings at the moment. He raised his hand, fingers into a fist as he allowed the ponytail to slowly slide from his grasp.
And there was his end.
Living the life of a peasant was one Zuko was not accustomed to. He disliked, no, despised his new life. He was royalty, and they should be the ones begging not him. One night, while they were sleeping in the forest, he heard a distant whisper calling out his name. ("Zuko, Zuko...") Opening his eyes, he scanned the area and hoped that it wasn't his sister playing some type of trick on him. It was only a few minutes later before he decided to lie back down to sleep, when he noticed something blue coming out of his traveling bag. He picked it up, but it wasn't the object he believed it to be. It was, instead, a cloth that his uncle bought the other day. ("It'll serve as a table, for now." his uncle told him that day)
For some reason, he hoped it was the blue mask. The next day, he saw a cart rolling down the market with masks on the back. One of them looked oddly familiar to that of his former mask. He decided to steal it when he had the chance...
It wasn't long before the Blue Spirit took over him again. He stole from others under the mask, and had no regrets. Once the mask came off, however, he almost felt a heavy burden on his shoulders. With every steal and thievery, the mask began to seep deeper into his skin and before he knew it, it served as his face.
His uncle took notice of this as well. The Zuko he knew and loved as his own son was replaced by an identity he didn't know.
He needed to figure out what he wanted to do, and begged The Blue Spirit to allow him to do so. (He didn't want to be The Blue Spirit, he wanted to be Zuko) He left his uncle, and tried to seek his own answers for once in his life. What he found only drove him more to become another identity. He was beginning to hate the life he had now, and wanted what was rightfully his.
He was stubbornly fumbling back to the role of Zuko, the banished prince who relied on a mask to serve as his only freedom. He should've been moving forwards to the role of Zuko, the refugee.
When he was reunited with his uncle, it wasn't on a good term. They had encountered not only Azula, but the Avatar and his comrades as well. Unfortunately, not even their forces combined with the Avatar's could stop Azula's ambush on his uncle. He fell to his knees and cursed his destiny; everything he had in his life seemed to be dying.
The water tribe girl offered her help, but he refused. He sent a blaze of fire towards them, ushering them violently to leave him be. He didn't want nor needed their help.
He was able to patch his uncle and help heal the wound Azula inflicted on him. (One of the many things he did right). During his lightning training sessions, Zuko felt hopeless and weak. The mask was calling to him again, but he ignored its call.
Later on, they were able to live as refugees in Ba Sing Se. The walls served as a prison to him, one that held within not only his physical being, but his spiritual self as well. Inside the great city he felt pressured even more to allow the Blue Spirit to take dominance over him. It called him every day and night, taunting him with its image inside his head.
He dismissed its call once again; the blue spirit thought him weak, but Zuko thought he was by far stronger than the mask and its powers.
However, when he heard news of the Avatar's bison missing, the call became greater and he soon fell back to his titular role. He told his uncle, and the only advice he could give him was that he should shape his own destiny.
He knew his destiny, and he wanted more than just serving tea. He wanted more, much more.
("I can give you what you want" it called to him that evening. "Make me your face, and I will give you that power you seek.")
He bided its call.
He felt freer than he had in a long time. Roaming the streets he felt no fear, no distractions and no restrictions. The chains given to him as Zuko the refugee was gone and broken by the fangs on the mask. He went and found the Avatar's bison (by holding one of the Dai Li by sword point), but his uncle found him once again.
"I know my own destiny, Uncle."
"Is it your own destiny? Or the destiny someone else is trying to force on you?"
"Stop it Uncle, I have to do this."
"I'm begging you Prince Zuko! It's time for you to look inward, and begin asking yourself the big questions..."
His teeth began to grind against each other, in an attempt to refrain from not yelling right then and there. He tried his best to contain himself, but the words his uncle continues to spout began to have an affect on him.
The mask noticed this, and prepared its defense.
"Who are you?"
That question felt like a heavy kick to his chest.
"What do you want?"
Time stood still, and he wasn't sure if it was his hallucination or not, but the mask seemed to come to life in the palm of his hands.
(It grinned at him; "You are me, as I am you." the blue spirit told him. "You want your destiny, and I can give it to you.")
He fought back. ("What can you give me that I already don't have?" Zuko questioned him. The words his uncle spoke to him were getting through.)
("Your honor and rightful place in the throne")
(In a sudden flash, everything became clear to him now. "You just want to control me.")
(The mask smiled deviously, and replied "I already do.")
Zuko cried in anguish and thrashed the mask, along with his twin-bladed swords across the floor and kneeled in front of the bison. All he wanted was a life he could choose on his own, to have the freedom he desired. It wasn't until now that he began to notice the Blue Spirit wasn't his freedom, but like Ba Sing Se, his own prison.
To save himself, just as his uncle told him to do, he threw the mask into Lake Laogai and left it behind. He didn't need to hide behind the mask anymore, and he realized: he was never The Blue Spirit, and he was never the banished prince with a scar, he was only himself. Without any restrictions left, and without a mask to hide behind, Zuko was finally able to be free.