Daniel.
BK to NJ, but always a New York Knicka
Harrison was shaky on the code and dark passenger stuff anyway. Dexter then broke the code by killing a good man just to free himself. Harrison didnt want to live a life of constant killing and on the run just to be with his dad. It wasnt the way he wanted to cope with his childhood and there was really no convincing Dexter otherwise. Look at all the people that died close to him when he could have turned killers in and saved lives. Only way was to get rid of pops. It sucks because we all like Dexter and dont really like Harrison, but thats the only way it had to end. Unless you wanted "suicide by cop" or to see Dex rotting in prison on death row.
Then there would be a clamoring for a new season with him in prison killing killers and to see him escape like Andy Dufresne to reunite with Harrison
I was half expecting Dexter to kill Harrison in that scene and for Bishop to role up on him mid/after kill.
If Dexter then killed her too and the show ended with him on the run, only for a post-credit scene where Dexter thinks he's safe, only for a Batista led squad to catch him as a segue for season 2.
Run it back as a limited the US vs. Dexter Morgan series, him standing trial or something. Have a season kind of like the Unabomber show on Netflix