I ' m not sure if that really indicates him changing into a more evil person . I ' m sure , if that was a human and not a host he would react differently . The very fact that this was a host , plus a host that was about to kill them , he realizes that they are not safe and are just wasting time with a host that will be picked up later anyways to be put back into rotation . Imho , that is a huge difference and doesn ' t necessarily indicate that he is about to go black . Yes , he somewhat changes his attitude towards what the hosts are and what decisions he can make in Westworld . But if we actually try to analyze him he has always been like that , he just never lost control because he was eager to maintain a certain image in society in order to achieve what he wants . He always was the obedient man , that keeps his anger under control the first time actually showing all those bottled up feelings when mocked constantly by Logan . So if the hat really got darker to indicate a change of character , that would be a pretty lame thing to do , since William doesn ' t really change he just opens up more , respectively is less nice to hosts , knowing that they are not human after all and what they feelexperience doesn ' t really matter .