Blindspot said goodbye for the year (don't worry, it returns Jan. 4) with a whopper of a fall finale that included spying behind enemy lines, an explosion that toppled a building on our heroes, and the reveal of Sandstorm's Phase Two.

But the episode was so juicy that there are more important things to discuss with Blindspot creator Martin Gero, whom we caught on the phone to break down the episode's even crazier events. Among those moments: Jane (Jaimie Alexander) "turning" Roman (Luke Mitchell), and the long-awaited reveal of the FBI mole (noooo!), plus what's coming up in the rest of Season 2 (hint: more Rich Dotcom and more answers).

TVGuide.com: There's so much to be excited about when Blindspot returns. What was your goal with this fall finale?
Martin Gero:
Well, I think that's exactly it. It's never fun to take about a month, month and a half off. We're back January 4. We wanted people to finish the episode, mark it down on their calendar ... and need to have to come back. For us, you know, we treat these seasons as two half seasons. Our fall finale is always a big deal for us. It means a turning point in the season and a shift in the storytelling, so we had a lot of big bangs and we tried to cram them all in there and not make it feel overly full, but we had a lot of ground to cover.

Blindspot fall finale: The mole is finally revealed

Jane made the huge decision to inject Roman with ZIP, in order to — in her words — help him "start over." Why did she think she had the right to make that choice for him?
Gero:
That's a tricky thing. At the end of the day, she probably didn't. I think she, over the course of this season, especially in getting to know Roman and Shepherd (Michelle Hurd), [saw] that what she thought was one of the worst things that happened in her life — her memory being erased — gave her a chance to free herself from a pretty vicious and intolerable past. She's been trying to subtly turn Roman for the past few episodes, but realizes at the end of this one that there's no turning him. He loves her, he can't kill her, but that doesn't mean he's ready to join her. In fact, he hates the FBI and I think is starting to regret shooting his mother, so she realizes the only way to save him is to reset him, so to speak. And it's an enormous gamble, and time will only tell if it pays off or not.

ZIP is an experimental drug. Should we expect it to affect Roman in the same way it affected Jane, or is there a chance it will react with him differently?
Gero:
It will react with him about the same, but when Jane came out of that bag, she was greeted as a victim and an ally. Roman is a known terrorist who just killed dozens of FBI agents. His time coming out of the fog of being zipped is not going to be as safe. He'll be faced with who he was a lot quicker, so it's going to be a very different experience for him, but a pretty fascinating one. The show has always dealt with themes of identity and who we are, so here we go. We've reset somebody else, someone who was exactly like Jane. So will the result be the same, or is there an innate goodness or badness within us? I think we tell those stories in a really neat way over the next 13 episodes.

What is the state of Sandstorm now? Shepherd isn't dead, and it seems like she knows how to hold a grudge.
Gero:
She's a pretty disciplined person, yeah. They've gone to ground, they've gone silent, which is terrifying to us because we knew they were the biggest terrorist group that America has ever faced. But at least we had someone inside. Now we don't have anyone inside, they've all disappeared. Now we drill down to the pieces we do know, the biggest of which is we know this has something to do with Weller. They've had their sights on Weller since he was a kid. Trying to figure out the why of that is our major lead in the opening episodes.

Just to clarify: Someone called Weller with a lie about Allie being hurt in a car accident. Was that done to pull Weller out of the mission in order to protect him?
Gero:
That's exactly what it was. Sandstorm was protecting him.

Borden (Ukweli Roach) is the mole! Did you realize that there were a lot of fans who suspected he was the mole?
Gero: Yeah, we have a very intelligent fan base, and the reality is it really could have been only one of three people. There's been a few polls floating around the internet, and [Borden] was kind of at 33 percent to 40 percent. Like, a third of the audience has guessed right. The reality is, for those who drilled down into it, he was the only new person, along with Jane, in the pilot. Not only that, but he was in an incredible position to keep her on mission, so to speak. He was the one who told her she can't quit the FBI, he was the one that started to plant in her head that she was starting to have feelings for Weller, he told Weller to open up about Taylor Shaw so that Jane subconsciously could have a lot of intel about her. It's the prime position. I think for those who are like, "Nah, I guessed [it]," the backstory to us was so interesting we really wanted to take the time, so even if you knew [it was Borden], the twist was the "why?" And I think the why is really interesting.

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You sold that really well, giving that backstory and how it related to the government mistrust of Sandstorm. And I don't know if I consider Sandstorm the "bad" guys, even if I may not agree with their practices. Do you think the way you're telling that backstory, it relates to the way things are in current events in the U.S. right now?
Gero: Well, all I'll say about that is that I've been getting a lot of tweets from people asking how they join Sandstorm. Like, an overwhelming amount of tweets asking where the Sandstorm sign-up sheet is. I think that's right. The interesting thing about Sandstorm this whole time is that I don't think anyone disagrees with them. They feel like the country is broken. I wouldn't murder someone to make that better, you know? Their methodology is insane and dangerous and inexcusable, but their core beliefs are something that people are really connecting with.

Knowing that Borden was the mole, how did you come to the decision to have Patterson involved in a romantic relationship with him? Storywise, using Patterson is tough because we all adore her and this thing went really far south for her.
Gero:
Sure. Patterson (Ashley Johnson) is our number-one favorite, sure, absolutely. It was tough, it happened kind of organically, it never was the plan from the first season to get them together but it started to make sense in a crazy way. And I think for Borden himself, I don't think he started that relationship to mine information from her. I think he genuinely had feelings for her, but it was insanely reckless of him to get in a relationship with her. He knew who he was and violated her in every way that you can to another human. He's not a good guy, even though in his heart he might feel like, "Well, I really loved her, so it was okay." He was not careful with her at all.

That really packed a punch.
Gero:
The good thing is we have the next half of the season, and Patterson is mono-fixated on bringing this guy down, as she never had been. The back half of the season for Patterson becomes a revenge story. Or trying to get revenge.

Based on that, can we assume that whoever got shot, it wasn't fatal?
Gero:
Uhhhh, possibly! That revenge story might end in the first episode back, we'll see. [Laughs]

I loved Tasha's reaction to Reade's confession that he watched Jones die instead of help him. How will their relationship move forward after this?
Gero:
I think Audrey [Esparza] and Rob [Brown] have been doing such beautiful work this season. It's added a lot of depth to the show, their performances, and it makes the show feel fuller. That's a storyline we're not letting up on, even though we know what happened to Jones. Now we need to find out what's going to happen to Reade. He's still dealing with pretty serious trauma. His relationship with Tasha will definitely be informed by all that.

We still don't know if Reade was actually abused by Jones, because he never watched the tape. Will we get an answer to that or does it even matter?
Gero:
All the signs point to yes, but we will find out definitely.

Back at TCAs, you said you would be toning down the show's violence as you moved to the 8 p.m. hour, and you would lean into more fun and light installments. We really saw that with the Rich Dotcom episode, as well as last week's hour. What's been the reaction so far to the change in tone?
Gero:
I think it's been pretty good! Our ratings are pretty steady and we're up in that time period from year to year, so I think NBC is really happy. For us, the show has always been, through this season and last, about balance and not having a predictable episode of Blindspot. We like to keep people guessing. It can't always be doom and gloom. We want to have a little fun every now and then, even in the dark episodes. They tend to be our most popular episodes. Rich Dotcom, you know, our Twitter mentions quintuple in his episodes. He'll be back, by the way, in Episode 14. For us, as creators of the show, we like to mix it up and have fun.

Before this season, you told us that we'd learn Jane's name and get a lot of her origin story. What's the big tease for the back half of Season 2?
Gero:
A lot of the question you've asked — like, why the tattoos, what's Shepherd's endgame — a lot of the big mythology questions are going to be answered in these next 13 episodes. And we have a twist ending that I hope... well, I don't want to give a lot away. I think there's a lot of fun to be had, even if you're a casual viewer of Blindspot. This next half of the season is more explosive and more fun, and we're able to turn more cards than we ever have before.

Blindspot returns Wednesday, Jan. 4 at 8/7c on NBC.