'Literally everything is darker,' she teased while speaking with ET via video chat.
The 22-year-old actress spoke with ET via Zoom this week, where she opened up about what fans can expect from the second installment of the hit HBO series.
"You won't even be able to guess what's coming... I couldn't even guess it," Sweeney, who plays Cassie Howard on the show, teases to ET's Katie Krause. "Creator Sam [Levinson] called me over the summer, going, 'So what do you think Cassie's going to do next season? Where do you think she's gonna go?' I'm like, 'I don’t know, maybe she does this or that.' He’s like, 'Ahh yeah. No!'"
"And then he read me a little bit, and I was like, 'Oh my gosh, wait!' I couldn’t even guess it, so if anybody's able to guess it, you’re very good," she continues. "It's just shocking. I mean, everything with life as a teenager is shocking, so you never know what to expect."
Sweeney also shared that "literally everything" about season 2 is "darker" as the cast is growing up and "getting into more intense situations."
However, it may still be a while until fans get to see what all goes down. The actress said that due to the ongoing coronavirus pandemic, production had to be shut down just as they were getting started on filming.
"They’re taking everything very seriously. They don’t want to put their crew or their cast or anyone involved in harm," she explains. "So they just want to make sure they’re staying safe and healthy. And waiting for all of it to calm down."
"I think everyone is hoping that [production] will be back sometime this summer, but they also don't want to rush anything just in case," she adds. "It isn't safe, so I don't think they wanna get too much hope in our minds and then have to push it longer. So we're kind of just waiting and seeing right now."
For those who have yet to watch season 1 of Euphoria, Sweeney offered some advice about the message she hopes people take away as they binge watch it for the first time while social distancing.
"I just hope that people take away the honesty and the pain that all the characters go through," she says. "That yes, there's so much going on in this one school. And so many people are like, 'That's so much.' But what they don't understand is we can't show 10 different schools in one show. So you have to take all these different characters and put them in one school."
"There's all these [different] characters out there somewhere," she adds. "Whether they're at the same school? Probably not, but they’re out there."
Sweeney, who is currently living in Los Angeles and away from her family, also talked to ET about what she's been doing to pass the time while quarantined. Because she loves to read, she recently partnered with Bustle to start her own virtual book club.
"I wanted to find something that could bring so many people together and I feel like that’s a very good way to get lost in a book," she explains. "So I started that, and I’m just working out a lot. I have this rooftop, I have this private area, so I've just been laying on the roof with my dog [Tank] and tanning."
"I've binged every show out there," she adds with a laugh. "I've watched Marvelous Mrs. Maisel, which was incredible, and then I watched Tiger King. I kept seeing all the memes! And I was like, what are all these memes about? I’m so confused! And then I watched it and I understand everything now."
Back in February, ET spoke with Sweeney's co-star, Storm Reid, who teased what fans can expect from her character's journey in season 2.
"I have no information, other than my character is supposed to be developing and becoming her own," Reid, who plays Gia Bennett, said at the time. "So I am very excited about that."
Hear more from the exclusive chat in the video below!