The 34-year-old actress also dished on her favorite scene from the series -- which was actually co-star Travis Fimmel's idea.
***SPOILER ALERT!! If you haven't watched Wednesday's episode of Vikings, do not read!!
And with that, it's time to bid farewell to Queen Aslaug.
Vikings said goodbye to Ragnar's (Travis Fimmel) second wife on Wednesday's episode, titled "In the Uncertain Hour Before the Morning," after she was shot in the back -- yup, you read that right -- by Ragnar's first love, Lagertha (Katheryn Winnick).
ET recently hopped on the phone with Aslaug herself, Alyssa Sutherland, who revealed that while her death might have left us with our mouths gaping open, Aslaug pretty much knew it was coming.
"She knows she's done," Sutherland said of Aslaug's thoughts just before her death. "I think she knows exactly what's going to happen to her. What's left is how."
How is right! Audiences watched Aslaug deliver one last "dig," in Sutherland's words, to Ragnar's former wife, as Lagertha agreed to Aslaug's surrender and request for safe passage out of Kattegat -- only to shoot an arrow into her back the moment she turned to leave. While the move might have been built up by "20 years of history" -- Lagertha told Aslaug she'll never forgive her just the episode before -- it's still a literal stab in the back. Turns out, Sutherland couldn't be more pleased with the result.
"I kind of love that whole scene for her," the Australian actress dished. "You sign onto any show, you know that you could go at any point. You don't know how long they're going to keep you [or] how long storylines are going to go. All you really hope for is that if you're going to go, you get to go out with a bang, and I was so thrilled when I read that scene."
"I sent [Vikings creator and writer] Michael [Hirst] an email immediately like, 'My goodness, this is incredible, and I'm so thankful,'" she added.
Sutherland is also thankful for is the closure her character received from Ragnar before saying goodbye.
"That was a huge scene. I loved that scene... I think all she's ever wanted is for him to be kind and tender with her," she confessed.
Sutherland also noted that it "was a lovely scene" before revealing that it was actually Fimmel's idea. "Michael told me that the scene was Travis' idea... if Ragnar was going to make amends with people, then he needed to make amends with Aslaug as well. I'm grateful for it."
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While Sutherland emailed a big thank you to Hirst, she's had to keep the news of Aslaug's death on lockdown to pretty much everyone else since the summer of 2015.
"I've been keeping a secret for over a year. It's not easy," she said. "We filmed it in October of last year, so I've known since I think August of last year. They gave me about six weeks of a heads up. It's been a minute for me to have to keep that secret!"
While most of the cast found out the usual way through reading the script, there was one person Sutherland said she had to tell ASAP: Maude Hirst, who plays Helga on the show and is not-so-coincidentally the daughter of Michael Hirst. Maude's sister, Georgia, plays Torvi.
"When I was in Ireland, I would live with Maude. We lived together each season, and we are, in fact, incredibly close. She's a dear friend of mine, and I remember going, 'Oh, I'm going to have to tell Maude,'" Sutherland revealed, explaining that she remembers very clearly stopping for "a six-pack or a bottle of wine" before heading home. "I actually think I forced a beer upon her. I was like, 'You need a drink.' She was like, 'Well, I don't know if I want one.' I'm like, 'No, I have something to tell you, and I just want you to have a drink.'"
As for what Sutherland -- who will next star in Spike's The Mist -- will miss most about her time on Vikings, she says it's without a doubt the people. "Our crew was so wonderful. It's pretty tough, after you've spent four years… you become so close," she told ET. "So to have these people in your life for that amount of time, and then to leave… that's the hardest part, I think."
Vikings airs Wednesdays at 9 p.m. ET/PT on History Channel.
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