[Warning: The following contains MAJOR spoilers for Shōgun Season 1 Episode 9, “Crimson Sky.”]

Romance was never top of mind for Anna Sawai‘s Lady Mariko in Shōgun, but there came a moment in the FX limited series where she could no longer leave the simmering feelings between her and Cosmo Jarvis‘ John Blackthorne on the back burner.

Mariko and Blackthorne slept together after she believed her husband, Buntaro (Shinnosuke Abe), died in battle. They never spoke of their “pillowing” after Buntaro returned, despite Blackthorne’s efforts. Duty to Lord Toranaga (Hiroyuki Sanada) and her murdered family surpassed all personal desires, but when Blackthorne stepped up to be her second as she was about to commit seppuku (suicide) in Shōgun‘s pivotal Episode 9, that was the “moment she realizes that what they share is much deeper than what she had anticipated,” Sawai tells TV Insider. “That’s the gesture that changes everything.”

Seconding her seppuku means striking the fatal blow. Mariko would first stab herself in the gut, and then Blackthorne would decapitate her as the tradition mandates. That he was ready to do this for Mariko was the ultimate symbol of Blackthorne’s evolution from the beginning of the series to now. It’s the highest sign of respect that he can give, as it prioritizes her cultural customs and loyalty over his own desires for her to keep living. And he begged her to keep living.

“He’s taking her over his own religion and beliefs,” Sawai explains of the powerful moment. “A couple scenes before that he’s asking her to keep living for him. And so I think that it just shows that he really, really cares, and that is the most romantic thing that you could ever do for someone that you love.”

Mariko was never in denial about her love for Blackthorne, even if she hid it deep within herself. “Circumstances are not going to let her be with him, and so you can’t keep chasing something that you’re not going to be,” Sawai says. “It’s not healthy to keep wanting to chase it, but it’s undeniable what they share. That connection is truly just their own thing. It’s very, very intimate.”

Mariko never believed they would end up together, but Sawai reveals that her translator definitely “holds onto” their connection as a comfort in tough times. She doesn’t let her guard down again, however, until circumstances push her to let go of all restraint.

Katie Yu / FX

“In Episode 4, when she does get with him, she believes that her husband is gone and she goes on this imaginary date with [Blackthorne] and they share something that’s so special,” the Monarch: Legacy of Monsters star shares. “She keeps holding onto that, but I don’t think it’s realistic for her to try to proceed with the relationship until Episode 9 when he shows her this gesture of love.”

They slept together once more after the thwarted seppuku. The energy between them in that moment was a defiant refusal to deny their feelings any longer, initiated by a yearning Blackthorne. But even if Buntaro had died, Sawai doesn’t see a world where Mariko and Blackthorne would have ended up together forever. “I don’t think it was realistic for that to happen,” she admits.

Mariko’s seppuku was stopped at the last moment by Lord Ishido (Takehiro Hira), but he sent a group of assassins to kill her later that night. When she, Blackthorne, Lord Yabushige (Tadanobu Asano), and other women were cornered and outnumbered, Blackthorne desperately tried to protect them from canon fire in a shed, whereas Mariko accepted death. “Anjin-sama, let it come,” she told her lover with tears in her eyes. You could see every ounce of love Mariko had for Blackthorne in this brief, tender moment before the blast killed her. Sawai played that scene as Mariko’s one chance to let all of her love for Blackthorne pour out.

“I remember just looking at Cosmo/Blackthorne and feeling like this is her goodbye. She’s not going to be able to come up to him and hold his hand and say this stuff,” Sawai shares. “It was wishful also to just accept your fate because that’s something that Blackthorne couldn’t do. He’s trying to control everything, and she’s just someone who’s like, we live and we die. We control nothing beyond that. She’s just looking at him like, I’m going to go, but thank you. And I hope you understand.”

Co-starring in Shōgun made Sawai and Jarvis close friends.

“While we were shooting it, we were just being professional and trying to be in our characters’ shoes, but we spent a lot of time afterward doing press, and I keep in touch with him and I know what he’s up to right now,” she says. “It’s been nice to just talk about the show after we’ve wrapped and see it from a different lens.”

See the aftermath of the gut-wrenching Shōgun Episode 9 when the finale airs this Tuesday on FX.