Maisie Williams on Arya's Killer Opening Scene in the GOT Premiere: "It’s So F*cked Up!" 

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Warning: This story contains spoilers for the Season 7 premiere of

to return, fans were greeted with a blood bath in the opening scene of last night\'s Season 7 premiere thanks to Arya Stark.

The lady-turned-assassin disguised as Walder Frey (a co-orchestrator of the Stark massacre known as the Red Wedding), held a feast for all of his relatives, then poisoned them by tricking them into drinking tampered wine during a fake toast. The Frey men dropped on the spot, Arya took off Walder\'s face to reveal her true identity, and she told a trembling onlooker: "Tell them the North remembers. Tell them winter came for House Frey.” Boom.

Arya disguised as Walder Frey in last night’s episode.

Viewers raved about the scene online, making Arya the most tweeted-about character from last night\'s episode. But today, we finally know how Maisie Williams, who plays the young Stark, felt about filming that killer moment.

"When I heard first heard about the Faceless Men, I always thought it would be really cool if she switched faces with a leading character rather than an unknown person’s face," she told

. "I really hope [viewers] don’t guess it’s her straight away."

Though Arya\'s retribution was inarguably badass, it did show a darker side to her than we\'ve ever seen before. "It’s so f*cked up!" Williams added. "Even Arya is surprised she has so much power. In that last moment she’s staring out at all those men dying, she’s turned into a bit more of a monster than she’s ever realized. I don’t think she’s sad about that but she’s got it on her mind."

Last night\'s slaughter marked the third time Arya has used her training from the Faceless Men to cross off a name on her epic kill list. The first was with Meryn Trant, the knight who killed her sword instructor Syrio Forel. She stole a face from the Hall of Faces and stabbed his eyes out in Season 6. The second was with Walder Frey—she slit his throat in the Season 5 finale after disguising herself as one of his servants.

Now that she declared she\'s en route to King\'s Landing to assassinate Queen Cersei, it\'s likely we\'ll see her use the same trick again for the other names on her list. Williams also thinks Arya\'s killing technique could lead to an interesting ending for the show.

"I’ve always had this fantasy in the back of my head—I don’t think it’s a good ending and fans might not like it—but that somebody would sit on the Iron Throne at the end and then they whip their face off and it’s Arya instead," the actress said. "I’ve always had that dream."

Long story short, everyone better stay out of her way this season. Watch the trailer for next week\'s episode, "Stormborn," below.

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