On Wednesday, Day makes her debut on the Syfy drama as book character Poppy, a dragon expert from Brakebills who crosses paths with Quentin (Jason Ralph), who’s sailing the seas in search of the next key. Although Poppy initially presents herself as peppy person, we’ll soon find out that there’s more to her than meets the eye, Day tells EW.

“She initially seems like a very upbeat, very frank person, and then as the episode goes on, you peel back layer and layer and she is a little more twisted than you think,” says Day, who is slated to appear in the next three episodes. “She might not be the best person to have on your side in some ways. The twists and turns that she takes during the episode are delightful because she is so eternally upbeat.”

A longtime fan of the books (and friend of author Lev Grossman), Day landed her part on the show after mentioning in a meeting with Syfy that she would love to guest-star. It just so happened that the series was trying to cast this part, which ended up reuniting Day with executive producer Sera Gamble, who previously enlisted to play hacker-turned-hunter Charlie on Supernatural. While Poppy and Charlie are both cheerful characters, Day says their similarities end there.

“Poppy is a really confident character,” she says. “She’s more mature [than Charlie]. She has a lot more going on and she has a lot of agendas. Poppy is definitely out for herself in a way that Charlie would never be. It was very fun playing a much different character.”

Poppy’s self-centeredness, when combined with her cheerfulness, makes for an interesting dynamic with the broody Quentin. “It was so much fun to play the scenes with Jason because Poppy is a very different sort of character than has been on the show before. She says exactly what’s on her mind. She’s very upbeat and sort of forces the other person with her [in a scene] to be on her bandwidth,” Day says. “Seeing somebody so positive and chipper on the outside has a really interesting effect on Quentin. Our scenes together were very, very fun to play with because it throws Quentin off in a way that’s kind of new to audiences.”

Adds Day, “As the episode goes on, she definitely steers the ship in very unexpected ways, [which] leads to some emotional stuff for Quentin I think people are really going to enjoy.”

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