SPOILER ALERT: Do not read if you have not yet watched “Unfinished Business,” the 20th episode of the 13th season of “Supernatural.”

Richard Speight Jr. has directed episodes of “Supernatural” before — starting in season 11, through season 12 and now two more in season 13. And while he considers each one challenging in their own right, he admits he never could have taken on “Unfinished Business,” an episode in which he had to direct himself as an actor in two distinct roles, had he not already stepped behind the camera on the show.

“When you’re directing an episode that you’re not in, it’s a big challenge. You’re already looking at an enormous cruise ship you’ve got to move nimbly through the water,” Speight tells Variety. “When you put yourself in the scene, then it’s a different animal. Each [episode] is its own challenge with a steep learning curve, but it was invaluable to have had that experience.”

Speight returned to “Supernatural” as an actor this season — for the first time since 2014 — with the episode “Devil’s Bargain” which revealed his character of Gabriel not to be dead after all, but instead imprisoned and tortured for years.

In “Unfinished Business,” though, he not only appeared as Gabriel but also Loki. As both the actor and director, Speight had extra freedom to “make specific choices” on how to differentiate between the characters.

“When you’re not directing yourself you’re reading the scenes in your head a certain way but you can get [to set] and the director has something different in mind, and you have to adjust,” he says. “I didn’t have that problem because I knew what I was thinking!”

Here, Speight talks with Variety about the new Gabriel, the importance of collaboration on the “Supernatural” set, and how he approached tricky scenes such as the fight sequence between Gabriel and Loki, the shootout in the dark, and Loki’s party.

What was the most important thing you did to prepare to direct the show again — and to direct such complicated scenes where you had to act against yourself?

What I found helpful was compartmentalizing — because to look at it as one giant elephant, it was more than the brain could comprehend. I remember the first time I talked to Jensen [Ackles] about it, he came to me and said, “Dude, have you seen the breakdown for the episode you’re directing?” And I go, “Yeah.” And he goes, “Your head’s going to explode.” Thanks for the vote of confidence! But that was the thinking [because] it wasn’t just that my character was in the show — he is the main guest star, and the second guest star is also me. It was a huge on-paper challenge [but] I have a really good rapport with Serge [Ladouceur], the DP, and Brad [Creasser], the A-camera operator, and they were enormously essential in this process. I needed to be able to rely on them — not just their aesthetic but their directorial eyes because I wasn’t going to do playback.

Why did you opt not to use playback?

I had a conversation with Jensen early on, and he’s directed himself as well, and he was like, “Don’t fall into the trap of getting playback. You will lose half your day rewatching takes.” And that was great advice. There were a couple of really technical shots that I would do playback on to see if it worked because it had to cut into something else but 90% of the shots I didn’t do playback. We would rehearse it [and] I had an actor double who knew all of my lines and was in makeup and hair like I was. I would watch the scene with the boys on a monitor and make sure the camera moves were how I wanted it, and then I’d go into the scene.

Was it just a big exercise in trust then?

I had a pre-episode dinner with Jared [Padalecki] and Jensen, who understood the task that I was facing and volunteered early on to “let us help you.” I trust them as actors, they trust me as an actor, and if we got in a scene and it wasn’t clicking, we’d tell ourselves we need another take. Jensen warned me my head was going to be spinning and [worrying about] where an actor is and if the camera crossed on time [and] “until you chuck that all fully, you’re not going to get the performance you want, so let us help you get there by being your sounding boards during the performance.” And starting day 1, they were that, and it was enormously helpful. Jared, Jensen, Serge and Brad — without them, it would have been very difficult.

The fight scene between Loki and Gabriel was pivotal to the story but also had to pose numerous new complications since you were acting against, and fighting with, yourself.

I was hanging my hat on the Gabe versus Loki fight because to see those two dudes in the room, first it’s going to be a novelty of “Oh my god, they’re in the same room!” But then you need to forget that and it needs to be a scene between two guys and a conflict and a resolution. And I feel like the scene works in that regard. I feel like first you go, “Whoa, they’re both there. This is the scene we’ve been waiting for” but then when you get into it, that feeling goes away and you start just looking at the conflict of the scene and how they’re interacting with each other.

What was the most important aspect to get right in that scene?

It’s all about performance to me. You can have clever shots, but if you don’t have the characters relating to each other and the performances aren’t believable, you don’t have anything. So I didn’t make that fight that complicated. It was still hard to shoot, don’t get me wrong, but it’s not a ton of visual effects, it’s not a ton of stunts — it’s bare bones, just a bar fight between these two guys.

What challenges did you find you were up against once you were actually doing it?

I shot the whole thing out of order. I shot the end first, and the middle second, and then the beginning. So Loki’s slow build during that fight is done completely out of sequence. So I have to know that so well in my head so that I perform it properly so that when I edit it together it looks like an escalation. At the end of the day, it was relying on my camera operators and Serge, the DP. But to be honest, we finished that scene with no seconds to spare in terms of how much time we could spend on it. We wrapped, and I went home, and the next morning I woke up at five in the morning and watched every frame of what we had shot the night before — and I found a couple of things we were missing. The fight between myself and myself was the second to last day of shooting, and the last day wasn’t a super heavy day, so [when] I realized the couple of things we were missing — and that was a product of I’m not the monitor vetting it, there’s no one there with my vision in my head, everybody can only do the best job they can do but nobody has my brain sowed into their head — so we started the next day by reshooting four shots from the fight scene. I used every reshoot angle in the final cut, and they were invaluable pieces to the puzzle.

There were many times in the episode where Gabriel was telling a story about Loki but the image stayed on you. And then in some moments, you did give glimpses of Loki as Gabriel described him, too. How much of when to see him was scripted versus your directorial influence?

I think Meredith [Glynn], the writer, and myself had the same idea, which was she had written very specific moments of “In the shadows, comes Loki.” It was Loki-light as Gabriel was telling these stories. And I went with that because I thought it was the right way to play it. So even when we see him, it’s on his back or his profile, he’s wearing a hat, it’s very shadowy and film noir-y. It’s very much on purpose.

To keep everyone guessing about whether or not what he was saying was the truth?

Because the audience — and Sam and Dean — are trying to figure out how much this is Gabriel telling the truth or jerking us around or Loki jerking us around. Even Dean was like, “Wait a minute, I thought you were Loki.” There was such a confusion. In the arc of the series, is Gabriel pretending to be Loki? Has Loki been yanking everybody’s chain and he’s actually been Gabriel the whole time? There are so many x-factors in the history of those two characters that we don’t know who we’re ever actually really seeing, and that’s kind of great! This many years later we’re not really sure who’s the actual, real one. So I played with that idea based on the ideas Meredith had in her script.

Was the idea of the shootout scene occurring only in pops of light also in the original script?

Meredith had the script say that Gabriel snaps and turns out the lights and there’s gunfire, and then the lights come back on and people are dead on the floor. So in figuring out how to do that, I didn’t necessarily want to have a black screen and “blam blam blam.” You could do that, but it’s not very cinematic. And there was a conversation with Serge and a couple of guys in the lighting department, and some research on other films, about how a muzzle flash is a light source and we could be stylized and play with [not knowing] where we are. My whole thing was, “Don’t worry about being over this guy’s shoulder here or there. Don’t create a geography, cinematically, in the room. Just create pops.” And every time it pops, you’re in a different spot — you’re on Dean, boom; you’re on Sam, boom; Gabriel’s not there, boom. There were all of these moments to create confusion so that nobody could really get a beat on somebody else. I thought that was an interesting way to quickly but cinematically tell an interesting story in that hallway.

Gun violence is such an important discussion these days. How did that affect what you did and the safety of the shoot?

I think the set has always been tremendously safe, to be totally honest. I’ve been on and off the set since season 2, and they take it very seriously…I’ve never even seen a rubber weapon on the set where the prop department didn’t walk over and show every performer and the director. They’re very adamant about being safe because the show is wall-to-wall action and there’s too much opportunity for injury — and for the humanity of it, and also for business, you need Jared and Jensen fresh and healthy every single day to make the best show. So it’s in everyone’s interest to slow down and take the time to rehearse it and do it the right way, the safe way every time.

Did you approach the “Casa Erotica” reference or party scene differently, given the climate around appropriate behavior with women on set?

100%. I think that aspect right now, for starters, you put out a casting call for porn stars and you’re not going to get a lot of excited actresses signing up. We made it abundantly clear through our casting person that that’s how they were described in the script, but as the director, this was going to be fun and funny — not skeevy. This bit should be “Gabriel’s Fun Party.” So I said, “Please, when you’re talking to these actresses, tell them to think Vegas party girl, not porn or not prostitute.” I wanted it to feel like girls at a party. Gabriel always experiences sexuality or the world he describes in “Casa Erotica” or the party sequences very much dripped in humor or wink-wink-nudge-nudge. And I think that helped you like the guy. It’s not gross. It’s not derogatory in the way it’s executed. And even more so in this case, I steered away from naughty nurse outfits or anything like that. And I put a guy in there, as well, to kind of mix it up and have both guys and girls as a part of that party crowd. I felt like we were able to approach it in a fun way. And I was very communicative as a performer to make sure the girls were very comfortable with what we were doing — even as something as innocuous as we’re all laying in bed, I wanted to make sure everybody was comfortable. Certainly the current climate is one that is all about “Let’s change the old ways, let’s change the ways we talk about certain things, let’s change the way we approach things” — and all for the benefit of women from actresses to executives to any job in any department anywhere. And I think it’s great — I think it’s a long time coming. It’s time to fold up the casting couch and put it out on the curb.

How much will Gabriel’s experience of being tortured for so long linger and affect his behavior, even after getting his revenge?

You can’t have that much torture and isolation and not have it be a permanent part of your DNA at that point. His sort of glib approach, when he starts to get mad at Sam and Dean, you start to see the veil chip away a little bit. When Dean is using the moral card of “You should have stood up for us, you should have helped,” he snaps. He’s like, “Are you out of your mind? The crap I’ve taken for the last seven years…” You definitely see an interesting side of Gabriel in those scenes where he basically says “I’ve been cute for about 15 minutes, I’m done being cute. I don’t give a crap about your issues, I’ve got a problem to solve because I just got my a– handed to me for seven years and somebody’s got to pay for that.” I think there’s something very interesting in the small revelations versus the big blowup. It’s about “This is what I’ve got to do for me. I may have run, I may have been weak at that moment or made a choice that you didn’t approve of — but I didn’t set myself up for seven years of torture, nor did I deserve it. We’re arguing two different issues. You don’t think I was a great warrior? Let’s have a debate about that — after I do a little revenge on these guys who made my life a living hell.”

Will you return again before the end of the season?

Well, as you see at the end of the episode, he does say, “A deal’s a deal. You helped me with what I needed help with so I’ll help you.” This may be the one time that Gabriel sticks to his word, I’ll put it that way.

“Supernatural” airs Thursdays at 8 p.m. on the CW.