Board Thread:Questions and Answers/@comment-86.24.72.42-20170222205736/@comment-5866730-20170320231357

It was plain to see that as much as Dexter cared about Harrison, he was too dangerous to stay with him. We saw how much he left Harrison in the care of another person. He never truly loved anyone in the series as much as he did Hannah. The only love he would've felt for Harrison and Debra was only due to human nature (i.e. family), however Hannah was different. He actually felt an immensely deep connection to her, enough so for his Dark Passenger to leave him for good, and for him to drop his murderous habits. This made him realise what his next best course of action is: Save his family from their biggest threat (which is him getting caught).