Prior to his birth, Gaara's hometown, Sunagakure, suffered a series of budget cuts, weakening the village's military strength with the expectation that it would continue to operate at its previous levels. Wishing for Gaara to be able to singlehandedly fill this gap, Gaara's father, the leader of Sunagakure at the time, had the One-Tailed Shukaku sealed within Gaara during his birth. Because a sacrifice was needed for the sealing Gaara's mother was used, and with her last breath she cursed Gaara and Sunagakure, hoping that her son might someday be the doom of the village.
In an attempt to help Gaara gain control over the powers granted to him by Shukaku, Gaara's father trained him continuously throughout his childhood. None of these attempts were successful, and Shukaku continually attacked those around Gaara. Though Gaara never had the intention of harming anyone and apologized profusely after each of his attacks, the villagers of Sunagakure came to hate him for the monster within him. His father, fearing what Gaara might someday become, deemed him a lost cause and sent assassins to kill him. With each assassination attempt over the coming years Shukaku protected Gaara and killed his attacker. His family having turned against him, Gaara came to believe the only person he could rely on was himself and, by extension, Shukaku.
As a result of his self-reliant philosophy, Gaara comes to believe that his only reason for existing and, therefore, the only way he can feel alive is by killing those who threaten his existence. During the Chunin Exam arc Gaara exhibits this trait through a variety of murderous tendencies, either by threatening to kill those around him or actually killing those who get on his nerves. As the arc progresses Gaara takes a greater interest in exercising this mindset on those of equal or greater strength than himself, as seen during his fight with Rock Lee. When Lee is able to land a blow on Gaara, a feat no other character had yet been able to accomplish, Gaara takes it upon himself to break Lee's body beyond repair. Though he is stopped before he can kill Lee, Gaara begins to obsess over finishing Lee off as punishment for his successful attack.
After his defeat by Naruto Uzumaki, Gaara, borrowing from Naruto's own philosophies, realizes that true strength comes from fighting for one's friends, not for one's self. Wishing to be just as strong as Naruto, Gaara abandons the belief that he is the only person he can count on and begins to rely on and mend his relationship with his brother and sister. Gaara's new view on life is first seen during the Sasuke Retrieval arc when he comes to the aid of Rock Lee. Noticing that Lee is still suffering from the injuries received during their previous fight, Gaara forces him to the sidelines and out of harm's way so that he doesn't injure himself further. This desire to protect others results in Gaara replacing his father as the leader of Sunagakure in Part II, as he longs to be able to fight and give his life for the villagers, despite their lingering distrust of him.
As the host of Shukaku, Gaara possesses the ability to manipulate sand, and as such can control it to fulfill almost any purpose. Because sand is not always in great supply where he fights, Gaara always carries some with him in a calabash gourd, which itself is also made of sand. In terms of attacks, Gaara predominately uses his sand to capture and then crush his opponents, only varying the size and intensity of the action to suit the situation. He can also solidify the sand into projectile weapons, copies of himself, and even platforms to allow him to move through the air. In terms of defense, Gaara possesses a sand shield that automatically reacts when he is about to be struck, even if he himself is unaware of an attack. Though this shield can surround him in an instant and protect him from most attacks, Gaara also armors his skin with a layer of sand just in case an opponent is able to bypass his defenses.
If need be, Gaara can channel some of Shukaku's strength for himself. To do so he simply layers sand onto his body and shapes it into a Shukaku-like form, giving him additional power and speed with each stage of its development. As Gaara gets closer to a full Shukaku form, he becomes considerably more bloodthirsty and violent. While he takes no issue with this side effect during his early appearances, this danger he can pose to other causes him to refrain from tapping into Shukaku in this way as the series progresses. Once he has fully layered sand onto himself, the Shukaku replica grows to life-size proportions with Gaara sprouting from its forehead. With this completed Shukaku form, Gaara can bring out Shukaku's spirit to battle in his stead by forcing himself to sleep, giving it control of the sand body. If he is awakened, either by his opponent or through his own efforts, Shukaku's spirit recedes and Gaara regains control.
Gaara, though playing a significant role during each arc he appears in, makes sporadic appearances throughout the series. He debuts when he is entered in the Chunin Exams taking place in Konohagakure, meant to play a key role in Sunagakure's planned invasion of the village. Though Gaara is intended to release Shukaku's spirit and attack Konoha from within while Sunagakure's forces attack its borders, Gaara's injuries from his fight with Sasuke Uchiha leave him unable to fulfill his part of the plan. Gaara flees the village to recuperate, though not before being forced into battle with and defeated by Naruto Uzumaki. After the invasion fails, Gaara is sent as a sign of good faith to assist Konoha's forces in stopping Sasuke from betraying the village. While he is able to help protect the Konoha ninja, they are unable to prevent Sasuke from escaping.
Two-and-a-half years later during the second part of the series, Deidara, a member the criminal organization Akatsuki, is sent to capture Gaara. When Deidara proves unable to accomplish this task in a fair fight, he threatens to destroy Sunagakure as a distraction, allowing him to defeat and capture Gaara. He takes Gaara to a nearby Akatsuki lair where he and his fellow members extract Shukaku from Gaara's body, resulting in his death. When a rescue team later finds his body, Chiyo, the woman who sealed Shukaku into Gaara's body years earlier, realizes that it was because of her actions that Gaara died. To atone for the mistakes of the past Chiyo transfers her life force to Gaara, restoring his life at the cost of her own. Though Shukaku is gone, Gaara retains at least some control over sand, though its exact extent has yet to be seen.