Because of the upcoming release of New Moon, there are alot of rumors flying around that werewolves have short tempers and are very volatile. This is part of the mythology of werewolves temperament that Stephanie Meyer has built into her werewolves in the book. The truth however is that not all werewolves are like this. The temperament of the werewolf is very much based on the temperament of the human that becomes the werewolf. If the human has a short temper and is volatile, so too is the werewolf. But a calm-natured, kind human is unlikely to change personalities once transformed. The only qualifier I want to add to that is that during initial transformations, many have found the process painful and confusing…sometimes first-time werewolves will be affected by this pain and confusion and may act out-of-the-ordinary when transformed. With time however, as they learn to control their transformations, their werewolf natures become more like their human natures.