I think one thing that needs to be mentioned to make things more clear is that Dexter is a serial killer, who views himself as a monster, but a 'good' monster insofar that he takes out other serial killers. Part of the problem with the series, imo, is that it never really made up its own mind, as to whether or not Dexter's behavior was ultimately immoral and worthy of punishment and/or legitimate consequence. Its position on the matter seemed to shift from season to season, sometimes in the same season.
I think one thing that needs to be mentioned to make things more clear is that Dexter is a serial killer, who views himself as a monster, but a 'good' monster insofar that he takes out other serial killers. Part of the problem with the series, imo, is that it never really made up its own mind, as to whether or not Dexter's behavior was ultimately immoral and worthy of punishment and/or legitimate consequence. Its position on the matter seemed to shift from season to season, sometimes in the same season.