Who has had the roughest past?

[Psyke]

Really? I thought Zabuza always thought of his childhood as happy times. Of course, those happy times were just him slaughtering the graduating class of the Mist Villiage, but hey - it's Zabuza. He enjoyed it. He hasn't been through anything very traumatic or troubling apart from he and Haku's deaths.

Ah I see.... For me I was thinking more on roughness and how many battles he's gone through while growing up, and not whether it was traumatic or not. As for the most traumatic growing up experience, I'll have to go with Gaara as well.