About

Haku was born in a perpetually snowy village in the Land of Water. During Haku's childhood, civil wars ravaged the Land of Water, and since those with kekkei genkai were commonly used as the most terrifying tools of war, many people irrationally dreaded and hated them. Haku's mother was one of these people, and attempted to hide that fact, eventually marrying and giving birth to Haku. Haku inherited her gift, and revealed their secret to his father while toying with his newfound power. Haku's father rallied a small mob and had his wife murdered. He would have done the same to Haku, but Haku inadvertently created of field of icicles though the house in his panic, killing both the mob and his father. Afterwards, he wandered the Land of Water as a beggar child until he was found by Zabuza, who agreed to take him in, warning Haku not to expect any companionship. Haku, for his part, accepted this readily, devoting his life to becoming the ultimate weapon for Zabuza. Haku accomplished this and more, becoming even stronger than Zabuza. Haku was fiercely protective of and devoted to the older ninja to an extreme, essentially becoming Zabuza's possession and asking Naruto to kill him when he feared he could no longer be useful.

Haku's kekkei genkai comes from his unique ability to use both wind and water-based chakra at the same time, creating ice, known as "ice release" (Hyoton). The First Hokage and Yamato have a similar kekkei genkai in the form of their "wood release" (Mokuton) techniques, which use earth and water-based chakra.

Haku is kind but straightforward, a drastic contrast from Zabuza. His personality doesn't appear to change from that seen in flashbacks of his childhood, which suggests that Zabuza's personality never rubbed off on him, but that is understandable. Zabuza didn't treat Haku as family, but rather as a tool to be used then cast off when no longer useful. Haku himself admits that he has trouble accepting the entire shinobi philosophy, as it requires killing, something which he despises doing and had avoided. The fact that Haku has never (intentionally) killed another human is a testament to his purity, something that Kakashi makes reference to in his eulogy on the bridge.

Haku knows a great deal about human anatomy, and can incapacitate or kill a person with a single needle. He demonstrated this when he managed to throw two needles into exact pressure points into the back of Zabuza's neck, making it appear as if Zabuza had died when in fact he was in temporary coma. Kakashi Hatake notes that ANBU members are taught to know every single detail of the human body, making it possible that Haku was trained there. It's equally possible, however, that he could've learned these skills from Zabuza, who was a member of the Kirigakure ANBU before defecting.

Haku also has an amazing gift of observation and deviation. He can witness a move just once and can easily find a way to counter it. Having only seen Kakashi's Sharingan once, he instantly devises its nature and comes up with a counter-strategy.
((Credit goes to Wikipedia.com))