Millie Bobby Brown Reacts to Viral 'Stranger Things' Fan Theories and Character Deaths (Exclusive)

ET spoke to Brown ahead of the release of her upcoming Netflix title, 'Enola Holmes 2.'

Millie Bobby Brown is addressing some viral fan theories surrounding Stranger Things.

ET's Rachel Smith spoke to Brown ahead of the release of Enola Holmes 2, where she shared her reaction to rumblings that Eddie Munson --who was killed in season 4 -- could return as Vecna's second in command when the beloved sci-fi series returns for season 5.

"I mean, it's a good fan theory," Brown said while still remaining tight-lipped about the show's fifth season.

She also addressed some of Stranger Things' most controversial deaths, including Billy, who was killed off in season 3.

"Yeah, it sucks sometimes," the 18-year-old actress admitted. "I loved Billy. I loved Dacre Montgomery, who was killed off in season 3. I had a really good relationship with him, so for me, it was really hard to let go of that. And the same thing with Papa in this season."

"I had a really good relationship with Papa," Brown continued. "I had a really good relationship with Matthew, and to let him go was really hard."

While Brown said she hopes the Duffer brothers bring back Papa for the show's final season, she maintained that she doesn't know as much about the show's plotlines as everyone thinks she does.

"I really don't know," Brown insisted. "People say, 'Oh, you can't say too much, like don't spoil it.' I'm like, 'Oh no, I wish I could spoil it for you, I don't know anything.'"

She continued, "They don't tell me anything. You could go through my phone right now. They never text me. They never tell me anything, because they know that I talk to people like you, and they know that I'm gonna spill the deets."

One thing she was able to spill the deets on: her Enola Holmes 2 co-star, Henry Cavill, a.k.a. Sherlock Holmes.

"It was really nice," Brown gushed when asked about working with Cavill on the sequel. "Just to be able to be with him again, and work alongside him. He's really talented. And to be able to be around him again -- he's such a seasoned actor, he's so wise, and for me to be able to watch that, and work with that every day, has been a dream come true."

See Brown and Cavill team up once again when Enola Holmes 2 hits Netflix Nov. 4.