Honestly I heard rumours about him when he was on Dark Angel, the stories were that he had something against Jensen Ackles in season 2 when he was brought on as the networks (younger and hotter) new star, so he would get really difficult over things like counting out their lines and making sure that he always had more. So it sounds like he’s been a bully for a while on top of everything else, and it’s very important to him to come across as the ~alpha male~ on set