Zuko has one of the wildest character arcs, not only in Avatar: The Last Airbender, but in fiction as a whole. From starting the series as a banished prince of the Fire Nation obsessed with restoring his honor in his father's eyes to ending it confronting his family and capturing his destiny for himself. All of these different Zukos are definitely different enough for us to assign a Zodiac sign to: which Zuko are you?
Aries - Zuko During His Agni Kai With AzulaPhoto: Avatar: The Last Airbender / Nickelodeon
Aries signs are characterized as uncomplicated, direct, and passionate. They are naturally headstrong and confident. Zuko realizes these qualities during his Agni Kai with his younger sister, Azula. Recognizing that she was not operating at her peak performance, he knew that he would be able to match her in a one-on-one duel, despite Katara being with him as back up. This is the Zuko in Avatar: The Last Airbender that has come to terms with his destiny, and is finally confident and self-assured in regards to his place in the world.
Taurus - Banished Prince ZukoPhoto: Avatar: The Last Airbender / Nickelodeon
Taurus signs are known for their persistence and their loyalty, which often comes across as stubbornness. Zuko most strongly embodies these qualities at the beginning of the series, two years after his initial banishment from the Fire Nation. Despite Fire Lord Ozai (and the Fire Nation, by extension) effectively turning his back on his son, Zuko is still fiercely determined to restore his honor and regain what he considered to be his rightful place in the Fire Nation. He projected these desires onto his goal of capturing the Avatar, and relentlessly pursued them across the globe, stopping at nothing to complete his mission.
Gemini - Zuko In Ba Sing SePhoto: Avatar: The Last Airbender / Nickelodeon
Geminis are often considered to be two personalities in one - they can be sociable and communicative one second, and withdrawn and restless the next. Zuko's likeness to a Gemini happens during the Fire Nation's invasion of Ba Sing Se. Zuko frees the Dai Li-captured Appa, and as Iroh notes, finally doing the moral deed has pitted his actions against the persona that he had constructed for himself for years. The conflict between these two halves manifest itself into a literal sickness, giving Zuko a fever and hallucinations. Zuko's two-faced character shows itself once more, when he betrays Uncle Iroh and teams up with Azula in order to capture the Avatar for the Fire Nation.
Cancer - Outlaw Zuko In The Earth KingdomPhoto: Avatar: The Last Airbender / Nickelodeon
Cancers are known to be emotional, loyal, and sympathetic, but at their worst they can be manipulative and highly suspicious of others. Zuko embodies these qualities as an outlaw in the Earth Kingdom. Having recently separated from Uncle Iroh, Zuko learns to fend for himself, but cannot help feeling sympathetic towards the civilians of an Earth Kingdom village who are being terrorized by power-hungry and abusive Earth Kingdom soldiers. He befriends Lee, the young son of an Earth Kingdom farmer. Zuko sees himself in Lee, and tries to protect him as best he can. Unfortunately, that required the use of his firebending ability, which inevitably fractured the relationship that he had built with the village's people.