Warning: Contains SPOILERS for the season 1 finale of Watson. Watson just killed a major character, but it probably wasn't who you thought. Both Stephens' and Adam's lives were hanging in the balance during the first of the show's two-part finale, and due to Moriarty's blackmail, only one can be cured. After flipping a coin, Adam is given the vector, leaving the team to find an alternate way to save Stephens in season 1, episode 13. Considering that both characters are played by Peter Mark Kendall, it didn't seem far-fetched that the show may part with one of the twins.

However, "Your Life's Work, Part 2" ends with the death of the show's "big bad" right after he and the protagonist finally come face to face. With the help of Ingrid, Watson infects Moriarty with a genetically engineered disease that only he can treat. The doctor forces him to cure Stephens, but rather than fulfill his end of the bargain, he watches Moriarty succumb to the illness. Several questions remain about the villain's motives, as he insists that his secrets die along with him.

I chatted with showrunner Craig Sweeny about Moriarty's shocking death, Stephens and Sasha's romantic moment, Ingrid's decision, and what to expect when Watson season 2 returns.

Sweeny Wanted Watson To Become His Own Man Outside Of Sherlock

"He comes into his own confidence by defeating the nemesis that had bedeviled him and Sherlock."

ScreenRant: You killed off Moriarty, the "big bad" of Sherlock. What inspired you to do that in the season 1 finale?

Craig Sweeny: It's funny. As a writer, whenever I hear the phrase, "Kill them off," I totally get where it comes from, but it's never how I approach it because it always feels like a glib thing. It felt to us, and has emerged out of a lot of discussion, and you could argue it was the right way, or even the only way to respond to the unique crisis that he had created where he had this extraordinary library of DNA.

He was capable of using it to kill basically anyone in the world without a trace that he had stolen the secrets of Watson's patients. It was not a vengeful act by Watson, but rather a prophylactic one to prevent the damage that he was able to do in the future with all of that DNA. As far as why now, I love TV, and I've always written TV and responded to TV that tells stories in chapters and that ends those chapters conclusively when it is time to do so.

And so I really did like, narratively, the idea that season 1 was the story of Watson becoming his own man outside of the shadow of Sherlock Holmes by confronting Holmes' nemesis and defeating him. That made sense to me as a way to firmly establish that Watson deserved the spotlight.

I love that you said that because it did cross my mind that Moriarty was always Sherlock's nemesis, not Watson's.

Craig Sweeny: When you have a show called Watson, right, the question of, "Well, why should we follow that guy?" hangs over it. One way is you cast Morris Chestnut, but the idea that he would earn his worth, and this is from the character's point of view, he comes into his own confidence by defeating the nemesis that had bedeviled him and Sherlock.

There's still so much that we don't know about Moriarty. Will season 2 dive into that or are those secrets really meant to die with him?

Craig Sweeny: The open questions about Moriarty remain open and of interest to us narratively. We're not setting out to craft a season that only looks back, but the overarching storyline that we do plan for season 2 will accommodate some further illumination of who that guy was.

Sweeny Debated Whether Both Twins Would Survive The Watson Finale

"It felt like it would've been a choice driven by the practical rather than the creative."

When you were crafting the season, did you always plan on Adam and Stephens both surviving? Was there a time when you thought one might not make it?

Craig Sweeny: That's a great question. Yes, there was. That's another example of discovering what you like about your show as you go and writing to that. Obviously, the idea of one performer playing twins has been done before, but one of the things that this show is attempting to innovate is doing that on a week-to-week basis on a network procedural.

And Peter Kendall has done such a good job with those roles that many audience don't even realize that's the same person. The open question for us was would that strain our resources so much that we wanted to only have one of those characters going forward?

And as we wrote the season and developed our production capacity to film Peter in both roles, I felt strongly that we weren't done with those characters. We were really only starting to get to know them. It felt like it would've been a choice driven by the practical rather than the creative, and so we decided to keep them both.

Stephens and Sasha have a near-death confession and a kiss. Where is their relationship headed in season 2? Are we going to see them try to navigate a romance?

Craig Sweeny: I think it's fair to say that that story definitely continues into season 2 in a surprising way in the wake of both of them having been through a pretty traumatic experience. There's a bond there that they're both surprised by and both really lean into.

Moriarty May Have Been Able To Sway Ingrid In A Different Timeline

"She connected more and more over the course of the season to both Watson and to Sasha, in particular."

Ingrid is my personal favorite character because she's so unpredictable. Did you want her to be truly tempted by Moriarty beyond being blackmailed?

Craig Sweeny: Yes. If we did our jobs well, I think that if he had approached her in a slightly different timeline than he did, he probably would've had a different result. She connected more and more over the course of the season to both Watson and to Sasha, in particular, but to the clinic at large.

And so I do think by the time he made his approach, what Moriarty underestimated was the nature of that connection. Ingrid, as we met her at the beginning of the season, it was a very open question as to which way she might've jumped, and then I think we earned her ultimate decision by virtue of what we wrote in between.

Could there be other people like Moriarty who know what she did to her father? Or is that a case closed situation for now?

Craig Sweeny: You never want to say case closed because you're cutting off options. I will say we plan a new and hopefully equally interesting arc with Ingrid in the second season, centered around the idea of, "Is it possible for that character to change her ways?" Can she change, not just her behaviors, but who she is at her very core? We will be looking more forward than backward, but of course, the fact that she did that remains out there and open to be revisited.

When Stephens told her, "I can't work with you anymore," she took that to heart. What does that say about Ingrid—that she would listen to him? She doesn't usually care what others want.

Craig Sweeny: I think we succeeded in putting her in a circumstance where she really had to consider the consequences of her own actions or become the kind of person who just doesn't care no matter what. She didn't know exactly what she was doing, but by virtue of what she did, she very nearly killed Stephens. Very, very nearly.

And we don't even know what side effects he might carry on an ongoing basis from that. It's not like he's just better, and it's all over. He's been through a lot of trauma and his brain was damaged. It was such an extreme situation that it was almost like cold water immersion for Ingrid where she finally had to consider the nature of what she did.

Season 2 Will Explore The Complexities Of Watson And Mary's Relationship

"I don't think either of them knows quite who they are as it relates to each other yet."

We also have to talk about Shinwell. I can't help but feel bad, despite his betrayal. Is there hope for him and Watson to ever be what they were?

Craig Sweeny: Based on Shinwell's response to what happened, I do think that the relationship is in a more repairable place than you might think considering the depth of the betrayal. Watson is nothing if not profoundly empathetic, and Shinwell is on the horns of a dilemma, and he did come forward and really change the course of that storyline. They would not have gotten the result they did without Shinwell. So yeah, I do. I think that that relationship can continue in some form.

Mary was quick to help cover up what happened to Moriarty, and she even gives Watson her blessing to move on in the same scene. I find their relationship interesting because it could lead to a romantic reconciliation, or just be a great example that platonic love can remain after separation. Are you leaning one way or the other?

Craig Sweeny: I don't think it would be fun for me to tell you. The most I'll say on that front is that they both learned in season 1 that there is love there, be it the love of friends or the love with the possibility of more—I don't think either of them know yet, and we're going to see them wrestle with that.

It's not closed off, but I don't think either of them knows quite who they are as it relates to each other yet. And then obviously the other ramification of that is, "What does that mean for the other people they're in relationships with?" It's a rather extraordinary thing to have such a close bond with your ex-wife.

It's one thing to say, "I used to be married," but to say, "I used to be married, and I work with her, and we're in a murder conspiracy, and we love each other," it makes their lives very complicated. So without revealing too much, it's going to be very fun to explore, and I think rewarding for the audience as well.

In season 2, can we expect more Sherlock Holmes villains, or will you be introducing new characters?

Craig Sweeny: The Sherlock Holmes canon will not go away. In fact, it will be present in a new and hopefully inventive way in season 2. It's not as simple as like, "Well, we did Moriarty, so now we'll do Gruner, and this time he's stealing the post-it notes instead of the DNA."

We work the lore in what I think is going to be a really pleasantly surprising way for the audience in season 2. But yes, we're not just saying the flavor of the stories, but actual events and characters from the stories will figure into season 2.

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About Watson Season 1 On CBS

A Medical Show With A Strong Investigative Spine

Watson takes place six months after the death of the titular character’s friend and partner Sherlock Holmes at the hands of Moriarty. The show stars Morris Chestnut as Dr. John Watson who resumes his medical career as the head of a clinic dedicated to treating rare disorders. Watson’s old life isn’t done with him, though – Moriarty and Watson are set to write their own chapter of a story that has fascinated audiences for more than a century.

Check out our other Watson interviews:

• Eve Harlow
• Rochelle Aytes

Watson season 1 is currently available to stream on Paramount+.