Zacharias is a truly unpleasant kid from Hufflepuff House. He plays Seeker for the Hufflepuff Quidditch team. He comes across our radar because he joins the D.A. But even though he seems actively to want to participate, he is incredibly snide with Harry. At the D.A.'s first meeting, when Harry suggests that they start with the Disarming Charm, Zacharias rolls his eyes and says, "Oh, please [...] I don't think Expelliarmus is exactly going to help us against You-Know-Who, do you?" (18.219). Harry informs Zacharias that he has used the Disarming Charm against Voldemort himself, but Zacharias continues to doubt Harry's every word. Fred and George make it their personal task to harass Zacharias since he's such a pill. But Zacharias keeps coming to the meetings anyway, despite the twins' pranks and his own bad attitude. It just goes to show two things: (a) Hufflepuff House (which has always seemed like the blandest of the four Houses) can produce jerks, too. And (b) you can be a hardworking member of the side of good and still be difficult to be around.