Haku was a villager from the Land of Water, and a member of the Yuki clan. He later became a shinobi after meeting Zabuza Momochi. Haku lived in a village where people with a kekkai genkai were feared and hated due to the pain the villagers had suffered from an earlier war that involved many kekkai genkai shinobi. When Haku's father discovered that his wife and child possessed a kekkei genkai (Ice Style), he assembled a small mob of villagers. With tears flowing down his eyes, he killed his wife, and then attempted to kill Haku. But before he could, Haku used his Ice Style to create several large ice spikes to kill his father and the rest of the mob.
In time, he was confronted by Zabuza Momochi, a man who had "the same eyes" as him. Zabuza later asked Haku to become his "weapon," which meant to become a dedicated shinobi for Zabuza. Haku readily accepted this role, due to the purpose it gave him, and devoting his life to becoming the ultimate tool for Zabuza to use. Zabuza then trained Haku in the ways of the shinobi, as well as every fighting technique that he knew.
Having been trained by Zabuza for years, Haku was a very dangerous ninja for his age. According to Zabuza, Haku possessed such prodigious talent that, in many ways, Haku had become more dangerous than him. One of Haku's defining battle-traits was his sheer speed. He was very fast with his attacks, such that Sasuke could not follow his actions until he had reawakened his Sharingan. Upon that moment, Zabuza was shocked that Haku would actually lose to Sasuke in terms of speed.
Haku's most noticeable power was the utilisation of water and wind nature manipulations to create Ice Style. His power over ice granted him special techniques, like the Crystal Ice Mirrors, which surrounds a target with mirrors that Haku could travel between and attack from, even if his opponent is in the sky. Haku possessed a very detailed knowledge of human physiology, thanks to Zabuza's former ANBU training. His knowledge was great enough that he could disable an opponent with acupuncture by hitting a precise point on the body with a senbon, to cause immediate death or a temporary appearance of such.
Tha latest Shippuden episodes with the revived Haku show him having lipstick. He may not have had it originally, but I like it, so that's why I added it to him here.
Especially how you draw him!