Even Jamie Campbell Bower Was “Quite Afraid” Of Stranger Things Season 4’s Vecna

His method acting once made Millie Bobby Brown cry.

Jamie Campbell Bower plays Vecna in 'Stranger Things' Season 4 via Netflix's press site

Spoilers ahead for Stranger Things Season 4, Volume 1. Keeping Stranger Things Season 4 villain Vecna’s identity under wraps was hardly actor Jamie Campbell Bower’s first experience guarding a supernatural secret from a fandom. In 2009, the London native joined the Twilight franchise as ancient Volturi vampire Caius, and, the following year, also began playing young Gellert Grindelwald in the Harry Potter universe, for example. Naturally, Stranger Things creators Matt and Ross Duffer weren’t initially forthcoming with that information — neither on nor off screen.

For Bower’s first taped audition, they used scenes from Primal Fear and Hellraiser, rather than any actual Stranger Things material. Only later did the 33-year-old actor learn a bit more about the character, and so he pieced the clues together himself. “I went crazy for, like, two days. In my apartment, I put a picture of Will Byers in the middle, and then all the other characters around it, and then sort of made this Claire Danes-esque from Homeland mind-map of who I thought this person was. I stepped back from it after two days, and was like, that feels kind of good,” Bower explained to Variety. “So I took a picture, and then I printed out all the pictures and put them in this little folder — and then I got a phone call saying Matt and Ross wanted to meet.”

At the meeting, the Duffer brothers revealed to him what Stranger Things would learn in the seventh episode of Season 4. Initially billed only as a “friendly orderly” at Hawkins Lab, Bower’s character was born Henry Creel, aka suspected murderer Victor Creel’s presumed-dead son. After Henry used his supernatural abilities to kill his mother and sister (also framing his father, in the process), Dr. Brenner (Matthew Modine) “adopted” him, changed his name to One, and began experimenting on him. Unable to control him, Brenner implanted a weakening and tracking device in his neck, essentially imprisoning him at the secret lab. One later tricked Eleven (Millie Bobby Brown) into restoring his powers, but after he massacred nearly everyone at Hawkins Lab, the young girl used her own abilities to banish him to the Upside Down. There, Henry took on a new identity: Vecna.

Bower’s commitment to the 10-page Volume 1 finale speech in which One explains all of this to Eleven in a flashback even made Brown cry. “She was terrified, like, literally terrified, and when she saw Vecna, she burst into tears and she said, ‘That’s not my friend. I don’t know who this person is anymore. Where’s he gone?’” he added to Variety, noting that he also drew inspiration from ’80s horror flicks such as Hellraiser and Nightmare on Elm Street. (Actor Robert Englund, who played serial killer Freddie Kruger in the latter movie, also plays the elder Victor Creel in Stranger Things.)

Yes, Bower also plays Vecna, using a deepened version of his own voice as well. The physical transformation process, which the actor previewed in a May 31 Instagram post, involved prosthetics and took roughly seven-and-a-half hours. To help channel the dark character’s “deep, deep, deep resentment,” Bower also went method, sharing that he “wouldn’t speak to people” outside of the production for at least four days prior to shooting his scenes. He would also sit alone in a “totally pitch black” room before filming, to fully get into Vecna’s evil headspace. About halfway through filming, even Bower himself “started to become quite afraid of Vecna.”

Ahead of Season 4’s final two episodes dropping on July 1, Bower also vaguely previewed a possible rematch between One and Eleven for Entertainment Weekly. “It gets bigger. If you thought that it was as big as it could get, it’s not,” the Mortal Instruments alum hinted. “It goes further, visually, story-wise, and emotionally for all the characters. It really is quite an explosive climax, let’s say. I know lots of people have used the word explosive and scope and scale, but I do mean that. It goes a lot further and we get to know more as well. We learn a lot more as an audience in these final two episodes, as well.”

As for whether or not he’ll be back for Stranger Things Season 5, Bower told EW that he has “had conversations about where the show goes in season 5,” but “couldn’t possibly give any spoilers.”