Although Dexter has led a peaceful life between the show's ending and the beginning of Dexter: New Blood, the life of major characters related to him drastically changes throughout the years. The controversial season 8 final episode, "Remember The Monsters?", left a bittersweet taste in mouths as there were too many loose ends. While new episodes and a real conclusion to the complex serial killer's arc arrived eight years after the final Dexter episode aired, New Blood did end with controversy again as they decided to kill Dexter off in "Episode 10" and undermined the character development and growth he went through in the original series.
Still, this did not mean there weren't any positive qualities to the spinoff. After Dexter faked his death and escaped in the finale, many questions arose as to what would happen to Dexter's son, Harrison, who had been left in the hands of another serial killer; what would Hannah be like as Harrison's guardian, and what was the fate of the various characters that were part of Dexter's everyday life. Most importantly, did any of the characters in the police division end up discovering Dexter's identity as the Bay Harbor Butcher. Dexter: New Blood answers many of these questions indirectly.
Dexter: New Blood Revealed That Hannah Died After Being Diagnosed With Pancreatic Cancer
Hannah McKay was Dexter's final love interest before New Blood and took care of Harrison after Dexter faked his death. Also having a dark passenger, Hannah was forced to flee Miami after she realized that the police knew of her identity, eventually settling in Argentina with Harrison. However, five years after their arrival, she was diagnosed with pancreatic cancer (and eventually succumbed to the disease). While there was an incline that she could be killed off since Yvonne Strahovski confirmed in an interview with HeyUGuys that she wouldn't be appearing on the new spin-off, Hannah's death did have a profound effect on several storylines (such as Harrison's mental health).
Harrison's Turbulent Life
Just like Dexter witnessed the brutal murder of his own mother when he was only a baby, Harrison watched the Trinity killer assassinate Rita Morgan as a child, which caused Dexter to think the only way to prevent Harrison from going down the same path. He decided that to protect him, it was best to stay away from him, leaving the boy with Hannah (who ironically is also a serial killer). However, Dexter finds out too late that things didn't go as planned since Hannah's premature death caused Harrison to be sent back to Miami by a social worker and move between different foster homes (since no one wanted the teenager).
Dexter also finds out that Harrison discovered he was alive thanks to the letters he had been sending to Hannah and that he managed to get Dexter's location by chance after encountering an Instagram post featuring Dexter/Jim Lindsay bowling in Iron Lake. This newfound discovery ended up affecting Harrison in the long run since Dexter's abandonment led to several important storylines in New Blood being (such as Harrison having a dark passenger himself, Harrison and Dexter having a strained relationship, as well as him becoming close to Kurt Russell, aka The Highway Killer, as he searched for a new paternal figure).
Dexter Found Peace, For A While
Since Hannah becomes a fugitive, Dexter decides to leave his life behind and flee to Argentina with her and his son, but Deb's death causes him to hang back at the last minute, and he decides to fake his own death instead, keeping a distance from his loved ones as he believes that's the only way to keep them safe. After surviving a hurricane at the sea and abandoning his boat's debris, Dexter settles as a lumberjack deep in the Oregon forests, forgetting his life as Dexter Morgan and living passively under a new identity, Jim Lindsay, gradually sending his dark passenger to a long slumber.
As implied by Dexter: New Blood, Dexter's only contact with the outside world was through letters he would exchange with Hannah McKay every once in a while. Convinced that he finally tamed his dark passenger, Dexter moves to Iron Lake to carry out a new peaceful life, where he lives until the events of New Blood. As years go by, Dexter finds a steady job that keeps him away from violence, a position at a local game shop, and begins dating the local Chief of Police, Angela Bishop. So much time has passed that even Dexter's dark passenger changed, giving way to Debra Morgan, his sister, instead of their father.
In a way, Dexter: New Blood is back to remind fans of how Dexter is devoid of any feelings and incapable to maintain authentic human relations. There's no such thing as a good serial killer, and it was just a matter of time until he gave into his impulses again. The original ending to Dexter's arc wasn't clear since his reclusion could wrongfully be interpreted as an act of redemption, although all those years away from violence and blood were merely a distraction. Some things never change but rather find shelter in hard-to-reach places: Debra returns as the ghost of Dexter's past, encapsulating all the rage and despair he has been repressing all those years.
Angel Batista's Was Promoted From Lieutenant To Captain Somewhere Between Dexter And Dexter: New Blood
Angel Batista was one of the most exciting cameos in Dexter: New Blood (although the character is completely wasted at the end since Batista doesn't get the chance to meet Dexter face to face after all those years). One of the best and most hardworking supporting characters of the original show, it wasn't surprising to see that he got a promotion in the Miami-Metro Police Department, leaving his Lieutenant badge behind and becoming a police Captain in the homicide department. From his insistent flirtations with Angela, it's presumed that Batista is currently single, although he could have had a wife in between Dexter and New Blood.
The Bay Harbor Butcher Identity
By the end of Dexter, it was left ambiguous by the showrunners whether the people from Miami-Metro Police Department discovered the real identity of the Bay Harbor Butcher, and Dexter: New Blood reveals that, after all these years, the case is still subject to controversy. From the way Batista talks like the killer and Dexter are not the same person, it's clear that he is unaware. However, this all changes when Batista goes through LaGuerta's archives and finds files pointing toward Dexter. As implied by Molly's podcast, the number of people who think the killer might be someone other than Doakes innocent increased a lot in the missing years too.
The Bay Harbor Butcher storyline always felt somewhat displaced from Dexter's narrative even though it represents the main character's villainous persona, an alternate devil Dexter himself must face. Although Dexter sees his code as a method of salvation, society doesn't discern the Bay Harbor Butcher from any other serial killer since it isn't any less cruel and brutal. In season 2, the storyline was completed in a rush with Doakes framed for the killings, just to be aimlessly brought back in season 7. It's a good thing showrunners finally committed to drawing the case to a close and exploring Dexter's darkest side.