The Magicians star Brittany Curran on Fen's 'heartbreaking' move

Warning: The following contains spoilers from Wednesday’s episode of The Magicians, “The Serpent.” Read at your own risk!

Fillory has a new high king.

In this week’s episode of The Magicians, Fen (Brittany Curran) overthrew High King Margo (Summer Bishil) and ascended to the Fillorian throne. However, the power grab definitely did not go down as we might have expected.

Last week, Fen received a prophecy from a magical creature, natch, that there would come a time when she’d have to dethrone Margo in order to protect Fillory’s future, even if it meant killing her. Naturally, that time came in “The Serpent.” When Ru (Rukiya Bernard), Queen of West Loria, arrived at Castle Whitespire for a state dinner, she told Fen that Margo had go if there was to be peace between their nations.

Josh (Trevor Einhorn) overheard the plot and warned Margo. Surprisingly, though, Margo didn’t try stop Fen. In fact, Margo commanded Fen to permanently banish her from Fillory so she could go on a quest to find special weapons (two ice axes) that could help her save Eliot (Hale Appleman).

Although Curran had been anticipating the scene where her character took Margo’s crown, she was surprised by how emotional she got while shooting it. “[Fen and I] were both so looking forward to becoming the high king and taking the crown,” the actress told EW when we visited the set in October. “It’s crazy because then on the day, it was actually really heartbreaking. On her close-up, I started crying because I really love Summer.”

“I thought she was going to be doing jumping jacks,” Bishil added with a laugh.

Curran also believes that Fen would cry, too, because she has come to admire and respect Margo over the past few seasons. “For [Fen] to have to do this to her, at this point in our relationship, is heartbreaking for Fen,” Curran said. “To finally have to go and forcibly take something from her, which Fen should have been doing ages ago with other people, but then to finally do it to the one person who has empowered her, was really, really hard. At the end of the day, Fen will do anything she has to do to save Fillory. Fillory comes first.”

Where does Margo go from here? Deep into the desert to find the ice axes that can expel the ancient monster from Eliot’s body. Her entire quest — which is based on a beloved sequence from Lev Grossman’s book series — is at the center of next week’s highly anticipated musical episode. “The story that [showrunners John McNamara and Sera Gamble] came up with is some of the best writing I’ve ever worked with,” Bishil said of the melodic outing.

The Magicians airs Wednesdays at 9 p.m. ET on Syfy.