Brad Alcerro is Harvey Kinkle's old best friend who moves back to Westbridge in the show's fourth season after living in Texas. Not much is known about Brad's life except for the fact that he has a step-father.
Biography
Brad dislikes Sabrina, seemingly for no reason, but it is revealed by Hilda and Zelda that he is a Witch Hunter. Brad doesn't know what he is, but whenever he is around a witch or magic is used in his presence, he senses it and immediately becomes cautious which is why he is constantly rude to Sabrina.
In the episode "Dreama, the Mouse," after Sabrina's tutee, Dreama uses magic in front of him, Brad declares his thinking that she is a witch which turns her into a mouse. Sabrina and her aunts then try to remove Brad's witch hunter gene or else Dreama will be stuck as a mouse for 100 years. They are successful despite the fact that Sabrina had Spring Fever, and remove the gene, which is literally a pair of tiny blue jeans.