Re: What you can deduce from these spoilers on the Dexter Season 4 fin
Wow. Even though it was predictable, Rita's death was still emotionally powerful. (Who else was yelling at Dex when he walked in the house, "Just grab your shit and go! Do not check messages, do not answer the frakkin' phone!!!"

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So how do you guys see season 5 starting?
Dexter won't cover up Rita's murder - there's no reason to. The cops will have security footage of Trinity waltzing into the precinct and speaking with Dexter, who will look like he was just trying to redirect a lost tourist. From that, it's easy to conclude that Trinity was looking for a victim among the people at the precinct and perhaps picked Dexter at random. He looked up Dexter's home address and killed whoever he found there.
Having Rita suddenly go missing would be far, far more suspicious for Dexter than the notion of her being the Trinity killer's final strike at the Miami PD. And I can't imagine Dexter allowing Astor and Cody to think their mother abandoned them. He'll want to give them the closure of a funeral.
I still think they might dabble in the notion of Dexter being suspected in Rita's murder. There's still the unresolved plotline of Masuka knowing that the Morgans were having marriage trouble and the neighbor knowing about Dexter's violent streak. The neighbor (Elliot is his name I think?) was in love with Rita and will be anguished at her murder. He will target Dexter as the "obvious" killer - using a Trinity copycat murder to cover up killing Rita in a jealous rage.
Elliot may not be able to convince the cops to investigate Dexter, but if he's determined and vengeful enough, he might just turn up some interestingly odd information about Dexter not directly related to Rita's murder.
Then again, sometimes the writers set up little plot elements at the end of one season and forget about them the next. That might be Elliot's fate.
Astor and Cody will be gone from the show for now - they'll live with the conveniently introduced grandparents. Dexter won't be able to bear living in the suburban house so he'll move back into his condo with Harrison. Maybe Deb will be there, too, like at the beginning of S2 when Dexter was taking care of her after the ITK.
Dexter will have to seriously question whether he can have anyone in his life - even Harrison (but where else does he go? I hope the writers forget Rita has a mother because I don't want Dex to have an easy out.) Doakes' dire predictions that Dexter will end up hurting someone he loves has come true (as I figured they had to - Doakes' dialogue had a Cassandra element to it.) If Dexter had surrendered to Doakes, Rita would be alive. Seeing him exposed as a killer would be less devastating for Rita, Astor and Cody than what has happened.
And keep in mind, everyone but Dexter will think Trinity escaped. Deb will be determined to track down Rita's killer, which means investigating Trinity's history while the rest of the precinct assumes he fled the country and will never be seen again. All it would take would be for Deb to interview Arthur's family and have one of them recognize Dexter's photo. It could be that same damn bowling photo at the precinct. Dexter better steal that and burn it. Or it could be a photo in Deb's wallet. Once Deb realizes that Dexter was paying visits to the Mitchell home while everyone was searching for Trinity - good gort!
I can see two ways Dexter can respond to this- he can either go off the deep end, or he can try to reign in the dark passenger in the spirit of what Rita might have wanted.
I think the purpose of killing off Rita is to force Dexter off the deep end, which is what they have to do for the final season. What I cannot figure out is how anything even remotely resembling a happy ending can be cobbled out of this horrific situation. Dexter has proven to himself that as long as the Dark Passenger is within him, he cannot allow himself normal human relationships. But there's no way to change that situation that stays true to the character.
I'm really puzzled how they plan to resolve this, and I don't want it to be tragic - Dexter being exposed, committing suicide, or cutting off all human ties. I want Astor and Cody to come back to live with their Dad and little brother, with Aunt Deb to help raise them. How the frak this could ever happen is beyond me. I hope it's not beyond the writers.
Someone by the end of next season, which I do not believe will be the last, will find out about Dexter.
I think Deb could find out a lot of the truth truth in S5 - specifically that Dexter kills "bad guys" but maybe not so much the reasons behind it - and keep quiet about it - especially if Dexter's murder of Trinity is the first murder she finds out about (and assumes it was revenge.) After that, it's a slipperly slope - if she condones one killing, why not condone them all? And her loyalty to Dex will be magnified after such a devastating loss.
S6 could be Deb slowly realizing that Dexter is truly the monster he says he is, yet unwilling to just turn him in. And that could be an incredible season.
But this won't work if Deb finds out that Dex was pussyfooting around with Trinity which led to Rita's death. So how about a mechanic at the Mustang repair place? We didn't see how Dexter sabotaged the Mustang. Maybe he wasn't as unseen as he thinks. The cops will trace Arthur's Mustang to that repair place and presumably find it abandoned on the side of the road. All it takes is one guy who saw Dexter.
If that one guy goes to the cops and reports what he saw to
Deb, her natural assumption would be that Dexter discovered Rita earlier than he let on; sabotaged the Mustang to get Trinity where he could be easily killed; and then disposed of him. Would Deb rat Dexter out if she assumed that was the sequence of events? I don't think so.
Harrison sitting in all that blood was clearly supposed to mirror Dexters own trauma, and it looked too staged to be a coincidence. But how did Trinity know about that?
I think that was a metaphor - Trinity might not have put Harrison on the floor there. Could have crawled in on his own. A "coincidence" like that is okay for artistic reasons. Also, he's too young to be traumatized in the same way Dexter was, so I certainly hope they don't take that further than metaphor.