Dexterous

A good friend has repeatedly complained that because he's a "big name actor" John Lithgow's season four character in Dexter was allowed to live far too long than any logic would dictate being permissible. I will agree that as far as our logic goes, Lithgow was allowed to live too long. I'll come back to this, first I want to address a common trend in how 'guest appearances' work on tv shows.

TV shows have guest stars all the time and they almost always fill one of two functions: they are a very short-lived character (1-3 episodes TOPS, almost always just on sitcoms) added in as a gimmick or ratings stunt (see Brad Pitt on Friends, Matt Damon on 30 Rock, John Larroquette on Law & Order and Jenifer Aniston on Cougar Town), or they are a long-term guest star, almost always brought in for an entire season, almost always on hour long dramas, and almost always as the season's major antagonist (see Adam Arkin in Sons of Anarchy, John Lithgow, Jimmy Smits and Julia Stiles in Dexter, and Garret Dillahunt in Deadwood, Terminator: the Sarah Connor Chronicles, The 4400, etc.) . Sometimes they're brought in for a different purpose, but then you can expect them to die. Often these season-length guest stars outlast the amount of time logic dictates they should.

This is so much the case in Dexter that I am going to go as far as to say that defiance of logic and sensibility is precisely a major character flaw of Dexter's. Dexter, because he sees traits in others that don't exist, but he desperately wants to exist because he wants those traits for himself lets characters live much longer than he really should. Dexter lets Miguel live too long because he mistakenly believes believes Miguel represents an idealized version of himself, and so he refuses to see the dangerous psychopath barely contained in Miguel until it is well and beyond too late. Trinity is allowed to live too long because Dexter is dumb and thinks he can learn how to be a good father and be a serial killer from Trinity when he should already know that Trinity is not him and can not model for him how he should operate his own life and livelihood. Lumen is going to be allowed to live too long as well. Like Miguel she is unhinged and Dexter is ignoring it. Why? Because he sees her rape revenge as an outlet for his own need to avenge Rita, even though he has already killed her killer.

In a nut shell, Dexter is a consistent idiot when it comes to not killing the right people when their time has come.