Warning: If you’ve yet to watch this Sunday’s Dexter premiere, avert your eyes now! Everyone else, read on…

Dexter on Sunday launched its seventh season with an electric hour that concluded with a development so major, it (almost) made the tragic murder of Rita look like child’s play.

A stoic Deb, having recently walked in on her brother offing erstwhile Big Bad Travis Marshall and consequently piecing together a few murderous mysteries from the past six years, confronted Dexter with the question he’d long been dreading: “Are you a serial killer?” And, in a moment of brutal and almost tragic honesty rarely seen on the Showtime saga, Dex confessed: “Yes.”

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Here, Dexter executive producer Sara Colleton shares with TVLine how the killer cliffhanger came about and why now was the time for Deb to learn all about her beloved “brother.” Colleton also addresses plans to once again address the possible romantic feelings between the sibs, La Guerta’s tireless quest for the real Bay Harbor Butcher and what dangers Dexter will face as the season progresses.

TVLINE | At what point did you realize that you would end the premiere with Deb discovering Dexter is a full-fledged serial killer?

We felt that after dancing around this for six years — when is Deb going to find out? — we would have cheated our audience to just put our toes in the water. We felt we really owed them for it to be that she now knows it all. That was the most honest and the most dramatic way to handle it… Once it’s out there, there’s no dancing around it anymore. Dexter starts out Episode 1 with all of those excuses at the church, and she sort of buys them… But you don’t leap from seeing [Dexter kill someone] to thinking, “My brother is a serial killer,” in one scene. Your mind would just block something like that out. But Deb is Deb, and when she gets a bone in her mouth, she is like a dog. [Laughs] She just starts calling him on everything and following her instincts. As much as it’s the series-long quest of Dexter’s to be known — and now he is known, with Deb — it’s also an amazing year for the character of Deb because you see her transition from this first-year, gawky girl who was in Vice to an amazing detective. Just as Dexter can’t stop himself, she cannot stop herself from being a good cop.

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TVLINE | How important was it for Deb to piece together everything she’d overlooked or tucked away in her memory since Season 1?

That is the way we approached it. We knew where we wanted to end up, so we trolled through the past six years, looking at the moments where she had [come] one step closer [to discovering Dexter’s secret], and then had her wonder how she couldn’t have seen that. That’s really how we plotted it out when we were talking through the first episode.

TVLINE | Talk a little about your thoughts on Michael C. Hall and Jennifer Carpenter’s respective performances at the start of the episode, in the church, and the end of episode, in the apartment.

It’s staggering. Their duets this season really are staggering. Finally Dexter is showing emotion because he’s no longer hiding, which we see in these scenes with Deb. And Michael is one of these actors — both of these actors are, actually — that have the most amazing ability to make any bit of dialogue seem honest and real and in the moment. It always feels as if they are saying it for the first time right then. There’s such honesty with both of these actors and such an ability to calibrate and layer their performance within a sentence, from threat to fear to love to suspicion. We are blessed to have both of them. I couldn’t imagine the show without either of them.

TVLINE | Deb chose not to reveal to Dexter why she was at the church in the first place, suggesting that she was not yet wanting to reveal her romantic feelings. Will that still eventually come to light?

We pride ourselves on never opening up a door that we don’t go into, fully explore it and then shut the door on it. So, yes, that shows up in the course of this season.

TVLINE | Did negative fan response to that controversial twist impact the choice to table it for a bit?

No, we’re dealing with it the way we had always planned. It’s a forum by which both of them eventually can really talk about their feelings. It really serves us this season. And you will see that when it happens, about midway through.

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TVLINE | It must be asked: Will Deb ever recall Rita’s murder and/or the Trinity case and question Dexter about it?

She’s going to go through the whole history of her relationship with Dexter and there will be continued surprises and discoveries that she will make that will cause her to cope in different ways.

TVLINE | What does Deb do with this information now that she knows Dexter is a killer?

There’s a denial process; she’s [convinced Dexter’s Dark Passenger] is an addiction and she’s going to watch him like a hawk. She’s going to trust him the way that Harry never trusted him and be there for him. Of course, it’s like lockdown for Dexter, but it does give him a tiny feeling of, “Is this possible?” He [will be] able to control the Dark Passenger for a moment, which is a huge step forward for him, and it leaves him thinking that if Harry had believed in him the way Deb believes in him, could it have been different? We drop such a bomb at the end of [the premiere], and then we have to play out every permutation that Deb is going to go through, which is now denial. Dexter, of course, would love to think that [rehabilitation] is possible on some level, so that’s really what Episode 2 is about, as well as introducing the great character of Issac (played by Ray Stevenson) and dealing with Louis Greene (Josh Cooke).

TVLINE | What is Louis’ issue with Dexter?

He is a weird geek, an Internet freak and an obsessive fanboy — he became obsessed with Dexter and got way into his life. It’s like a fan stalker.

TVLINE | Wouldn’t someone as paranoid as Dexter have password protected his computer?

[Laughs] Louis is a computer genius. He made his money as a tech guy. Kids who grow up with computers can bypass anything.

TVLINE | Let’s talk about La Guerta finding the blood slide. Is she thinking that the Bay Harbor Butcher is still at large?

In addition to the Deb of it all this year, there’s the whole threat of La Guerta, who has discovered a blood slide at the Travis Marshall burn site. As a fan of the show, you know that she never believed that Doakes was the Bay Harbor Butcher — she had gone to great lengths to try to prove that he wasn’t — and that he was the great love of her life. So, she starts getting this suspicion and it’s a trail that we know is going to lead eventually to Dexter. But she just won’t let go of it because she’ll become obsessed with proving Doakes’ innocence.

TVLINE | Obviously, Miami Metro is going to continue the hunt for Viktor as a means of avenging Mike’s murder. Will it come to light, at least for Deb, that Dexter offed him?

It eventually will, but Dexter [killing Viktor] and venting his pent-up anxiety does bring in another season-long threat to him in Ray Stevenson, who plays the head of the Ukrainian mob. He’ll come to Miami to investigate what happened to his very trusted Viktor, and of course that is also going to bring him into direct confrontation with Dexter and Miami Metro. Dexter unleashed in the first episode in seemingly irrelevant ways — Viktor’s murder being one of them — that are going to loom very large as possible dangers as the series progresses.