Spoilers ahead for Outlander Season 6.

When Claire used ether to shut off her traumatic memories at the end of the Season 6 premiere, the move divided the Outlander fandom. And whether you liked Claire's coping mechanism on Outlander or not, the director of "Echoes" and "Allegiance," Kate Cheeseman, knows you have thoughts.

When I bring up the ether — and the reaction to it — during a phone call, Cheeseman starts laughing. "I know. I know," she says. She points out that the ether was in the script, so the writers were responsible for the choice. (Executive producer and showrunner Matthew B. Roberts wrote the premiere.) But she stands by the plot, pointing to Claire's need for peace and "undisturbed sleep."

"The feeling was that every time she goes to sleep, she has these bad dreams and flashbacks of Lionel and the Browns. And the thing about ether is it just completely cuts you off," Cheeseman says. "So if you're drinking, it's not stopping memories, is it? It's just softening things, or it's just like distancing things," she adds, perhaps in response to some fans wondering why Claire didn't rely on her go-to substance of alcohol. "She knows what drink does and that drink doesn't silence your brain."

She points out that Claire abusing her latest medical experiment wasn't premeditated — something Caitríona Balfe had mentioned in an interview with The Dipp as well.

"Initially, she's just experimenting because she wants to find a way to operate on people which is better than drink, where they don't react," Cheeseman says. "So ether's going to be a godsend or save people's lives. But you need to know how many drops. So what she's doing is taking two or three drops and timing how long that lasts." She does point out that while it's "relatively safe," the 20th-century doctor would know the dangers of it. But her post-traumatic stress has led her to this drastic form of coping.

"She wants just to be shut off from these horrible memories that keep happening," Cheeseman says. "It's the only way to shut out the ghosts."

In Episode 602, "Allegiance," Claire relies on the ether after she sees Lionel Brown in the window of her surgery door following Marsali bringing up the attack. Cheeseman explains that originally in the script, Claire was supposed to have seen Lionel outside through the window. But the director switched up the location of the specter to be at the door of Claire's surgery. "I wanted them inside because I felt like if he was in the window as she was looking out, it would be outside her space."

"I thought with the door that you've got that thing where you open a door and you see a reflection behind you, but when you turn, there was nobody there," Cheeseman says. "It made it really clear and yet also gave her the chance to shut the door and fall against it when she realized there was nobody there."

"It's the only way to shut out the ghosts."

Plus, she notes, seeing a reflection is a tried and true horror technique — citing that it's featured in the movie Repulsion and she's utilized the method before in a horror short film.

"It looked like he'd invaded her apothecary, which is like the heart of where she is," she says. "I wanted it to look like he'd come right into her most important part."

She also used reflections at the end of 601, "Echoes," when Jamie's concerned for Claire after she wakes from her nightmare right before she abuses the ether for the first time. "I was trying to get some sort of reflection of Jamie looking at Claire," she says of him looking at her in the mirror. She compares him watching her to when he saw a vision of her as he was getting flogged in Ardsmuir. "You're always looking for things like that, which I think bring out how people are."

Along with the thoughtfulness that went into filming these moments, there was a fair amount of research that went into creating the ether storyline.

"I wanted to check that we were doing the ether right and the equipment. So I've got two friends I went to university with — one's a professor of chemistry and the other one's a research chemist. And I emailed, 'So, I've got this scene around making some ether. Can you just check that this is right?' And I got this panicked phone call saying, 'You're not really going to make it are you?'"

Besides the dangers of creating ether and inhaling it (Cheeseman notes that the impurities when you distill it are what's "really bad for you"), there was also the concern of its flammability. Viewers couldn't help but notice the number of candles Claire had lit around the ether in the season premiere... especially since Claire knows she's supposed to die in a house fire.

After our conversation, Cheeseman emails me unprompted to defend all the open flames (and to give me some fun tidbits about 19th-century ether parties, or "frolics," to provide context about how the drug was used in the past).

"It is true that it is highly flammable but it gets much more flammable as it breaks down and changes with light, which is why it is stored in brown bottles. So it is more dangerous the older it is," she writes. "But you have to remember that in those days, there were no other source[s] of light or heat, so they had to use candles. However, as long as they aren't directly next to each other, it won't spontaneously explode or catch on fire and we were careful to keep them separate."

Outlander author Diana Gabaldon wrote something similar about the ether's flammability in a thread on TheLitForum. And like Gabaldon, Cheeseman has a science background, noting she studied zoology, subsidiary chemistry, and biochemistry in college. "It was all very carefully researched by everyone and I triple-checked with my chemist friends."

Although viewers (and book fans, in particular) may still take issue with Claire relying on a substance to cope with her trauma, at least Cheeseman's insight into the filmmaker process should alleviate concerns that production didn't think it through. And if that's not enough, there's always the fact that Gabaldon previously told The Dipp that this controversial storyline will have a good payoff. "It is very plausible and moving," Gabaldon said. "And it does have a satisfactory conclusion."

This interview has been condensed and edited for clarity.

Images: Starz