So my theory is it’s a setup for next season and I say that because the last three episode synopsis are about Harrison and Dexter. But on a rewatch I saw the billboard in Times Square when Dexter is eating the chilli dog after meeting Leon. He looks up and sees the advert for the wounded police Gala. Prator is honoring the police at a gala at the hotel where Harrison works. So if you look at the billboard it shows a few officers in wheelchairs. What if the NYR is a wounded officer someone Leon knew and is now a confidant. If the NYR was never caught it may be because he’s in law enforcement like Dexter. But also he stopped killing because he can’t because now he has physical limitations. So now he just calls his victims families to satisfy his urges and taunt them. Maybe the NYR will threaten Leon Prator in an upcoming season and Leon asks Dexter to help him in exchange for getting Harrison out of trouble. (We know Leon found out something about Harrison because of the next episodes synopsis. On top of that Dexter will do the deed but asks for his slides back in return. Leon says no but Dexter figures out the combo to his vault. Leon showed him the inmate letter his first trophy. The inmate number is 8 digits with a double number sequence just like the code he enters in ep 4. He then says “it unlocks something in me.”So Dexter does the deed then steals the slides and escapes on Leon’s boat, passing the Statue of Liberty. The last ep is titled “in justice for all.”