"It was the seismic event we needed in order to do certain things in the future," teases showrunner Carlton Cuse

[Warning: This story contains spoilers from the season two finale of The Strain, "Night Train."]

Heading into the second season finale of The Strain, it was safe to say not all of the characters would make it out alive and well. With Setrakian (David Bradley) and Fet (Kevin Durand) bidding against Eichorst (Richard Sammel) for the Occido Lumen and Eph (Corey Stoll) and Nora (Mia Maestro) attempting to get Zach (Max Charles) out of town, the stakes were higher than ever.

In a new twist not seen in the books from Chuck Hogan and Guillermo del Toro on which the FX series is based, it was Nora who didn't survive the final moments, when Kelly (Natalie Brown) finally snatched her son back, infecting Nora in the process before Eph could come to her aid.

To find out what went into that shocking twist, what's ahead for Eph now that Zach is in the hands of The Master (Jack Kesy), and where the gang goes from here, The Hollywood Reporter caught up with showrunner Carlton Cuse.

In the books Nora is one of the few survivors. Why kill her off now?

Guillermo, Chuck and I had a lot of conversations about the show and its direction. We wanted to be sure the series had its own set of surprises. As we evolved the narrative of the television series, it has become distinct from the books and expanded out from them. Based on other things we’re going to be doing downstream, the death of Nora was a painful but necessary turn in our plot for events in season three. It was the seismic event we needed in order to do certain things in the future.

Can you tease some of those turns?

Nora’s death was something that would be immensely impactful to Eph; it spins him out in a new direction. Creatively when you spend time, work on it and think on it a lot, you’re constantly coming up with new ideas and approaches. That’s what we’ve done, explore avenues beyond the books to make it its own story.

Would this death have worked without the flashback scenes in the penultimate episode?

We did the flashback to try and give it more resonance. If we were going to see that character die then we wanted to have a more complete sense of the relationship with Eph. It seemed like a good idea to give the audience a sense of how they fell in love; what led to the start of their relationship before showing how it ends.

Nora had Kelly beat until Zach interfered. How do you defend Max against a lot of the Internet hate for that character?

People are being unnecessarily hard on Max Charles. He’s doing a really good job and really contributes to the show. He’s in a tough spot because inherently there are some things about the character that are not that likable. That is part of the narrative in the books. It’s a challenge to play that part; we see a lot of kids on television that fall into the category of a nice kid. It’s more complicated than that. Clearly in the books the character gets put in a very dark place and that’s an interesting story to us.

For followers of the books, was there any discussion of going ahead with Setrakian's death instead?

David Bradley is so much the heart and soul of the show. There’s so much that’s compelling about that character and he’s central to the narrative. He’s the character who’s meant to decipher the Occido Lumen, which is key to whether they can stop this plague. So yeah, that character was hugely important to us and I can’t imagine him better played than by David Bradley.

What does Eph looking for his son next season look like?

It will factor in a number of ways. Eph is concerned with, has he son been turned? Has he been changed? What is The Master’s intent and what does he hope to gain from this? What is the ultimate motive? All those questions are racing through Eph’s mind and he’s on a quest to get his kid back. But it’s not a completely direct path.

Nora wasn't the only casualty; Coco (Lizzie Brocheré) also died a second time. How will that impact Palmer (Jonathan Hyde)?

It was a cool arc for Palmer to fall in love and experience something that most people experience really early in life. He hasn’t experienced that until he was an older man, and that seemed like a powerful story, especially if he was going to lose this person at the end of the season. Her death becomes a big, catalyzing event for him that really has repercussions peering into the third season. We love the tense and competitive alliance between Palmer and Eichorst, and Coco was a great foil in the middle of that. Her death creates a significant rift between them that has major repercussions in season three.

It is hard to imagine him working for The Master now.

The question is, does he have a choice? That’s ultimately the question that Palmer has to deal with: is there an alternative or is he stuck?

Dutch (Ruta Gedmintas) wasn't in this episode. Is the plan for her to return as well?

We struggle narratively to serve all the characters on the show, and to just wedge her into the finale for the sake of having her in the finale doesn’t do service to the character, the actor or the story. So we finished Dutch’s story in [episode] 12. But she is very much a part of our plans for season three.

How will the group dynamics change next year?

There’s been a bit of a scattering into the wind by the end of the season and it forces the characters to examine how much they all mean to each other in this newly unfolded world. The questions are, when do they get back together, who does get back together and what for, and how? All those things become a part of the story telling in season three.

The Strain returns to FX for a third season in 2016. What did you think of "Night Train's" twists? Sound off in the comments below.

Twitter: @amber_dowling