Charlie Hunnam’s girlfriend just wanted him to come back as himself.

As he prepared to take on the role of graverobber and serial killer Ed Gein in Monster: The Ed Gein Story—the third installment of Ryan Murphy’s Netflix anthology series, streaming now—the actor was armed with girlfriend of two decades Morgana McNelis’ stipulation for him taking on such a dark character. As he admitted, she’s seen first-hand the toll these kinds of roles have previously taken on him.

“She got frustrated with me showing up and being a bit of a shell after doing a role,” Charlie recalled to E! News in an exclusive interview. “So, she said to me, probably about 10 years ago, ‘Here’s the rules of engagement: Go do your work. Be as selfish as you need to be, but then take some time, because when you get back, you better be ready to see me.’ Which is completely fair and really lovely.”

So indeed, after wrapping the crime drama, Charlie took some time to fully disengage from his time playing Ed—who was convicted of 2 murders and suspected of more—not wanting to bring the bad energy home with him.

“I take a week, at least, however long I need once I finish,” he explained. “This time was the most extreme decompression, because I was in Chicago, which is close to where Ed Gein lived in Wisconsin. So I drove up and spent the day and visited his grave and spent some time with him, which was a healing way to say goodbye and put a full stop at the end of the thing.”

So, knowing he would take the time to come back to her as Charlie, Morgana was more than supportive of the Sons of Anarchy star taking on the role.

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“My partner had incredible conviction that this was an important thing to do,” Charlie said. “She’s a great fan of the psychoanalysts, so she understands shadow work and the value of staring into the abyss and confronting the darkness much more than I do. So she was an amazing support to me, saying, ‘You just got to go do this thing, you got to enter the cave and face the dragon.’”

And face the dragon he did, delving deep inside himself and the mind of Ed to bring this role to life.

“I felt a huge obligation and responsibility because he was a real person, and also exacerbated by the fact that he had committed all of these terrible crimes,” the 45-year-old explained. “I wanted to find the truth of it. Right from my early conversation with Ryan, we were less interested in what he did, but we really wanted to understand why he did what he did, and take the audience and take ourselves through that journey of understanding how a human being becomes a monster.”

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It’s those underlying psychological questions of how and why that guided Charlie, too, as he considered whether to take on the role.

“I’m not a fan of horror and dark, bleak stories at all,” he confessed. “I really did grapple for a little while with the responsibility and the ethics. And I do believe—with the attempt not to sound highfalutin—but I do think that there is a value to storytelling in helping us to understand ourselves. And evil and darkness is part of the collective human experience.”

So, he added, “Telling stories about that and giving us a way to confront the boogeyman is valuable. As long as it’s done responsibility, as long as it’s done through the lens of actually trying to really explore like human psychology, then there is value to it.”