I do think we will learn shes not as much like Dexter as they want us to think. Its a common theme in the show that other killers are nothing like Dexter and hes a one of a kind, because of his dad and his trademarked Code. Lumen is the only other one I can think of that was shown to be truly similar, but she was out for personal vengeance and once she accomplished her goal, she resumed a normal life, at least as far as I recall. LV probably was setting Red up, and might have tried to kill Dexter had he got in the shower. Guess well see as we learn more about her, but I fully expect shes not a pure vigilante.