To watch Euphoria is to experience sensory overload. High school is hyper-realised in the HBO series, with every shot captured on grainy, textured film, every character drenched in neon lighting, and every costume meticulously mapped out from the hair to the shoes to the show’s now-iconic nails. At the centre of it all is Rue, played by Zendaya, who narrates the show as a fly on the wall: she’s our main character, but among her peers, she’s a mere silent observer.

The bold, immaculate looks of Rue’s peers stand in contrast to her baggy tees and long, unruly hair. For Zendaya, who’s an executive producer for Euphoria as well as its lead star, it’s a far cry from the elegant and iconic red-carpet looks she’s become renowned for (often a collaboration with her long-time stylist Law Roach). 

“This isn't my most glamorous role,” she laughs. “Which I love. I'm very grateful that I just get to wake up and roll out of bed and just go on camera.”

For Euphoria’s second season, Zendaya was less involved in the costuming as she was in season one, which she credits to Heidi Bivens, the show’s costume designer. “I trust [her] so much, that I'm just like, I know you know what you're doing,” she says. “She thinks about everything: the color, the emotional color that it represents for the character, it all has a reason.”

It was also key to her performance that Zendaya paid as little attention as possible to Rue’s clothes – particularly as Rue swerves down an even darker path of drug dependency than she did in season one. “Rue was at a point where there's a lot of dark tones for a reason in what she's wearing,” she says. “There's a reason why I didn't think about her outfits enough, because if I'm Rue, I'm not supposed to be thinking about how I'm dressing, because that's the last thing that Rue is thinking about. I think I inherited that for Rue, where I was just like, ‘I don't know, whatever I'm in, I'm in. They're… clothes.’”

Her red line, however: Rue’s shoes. “I have a superstitious thing with my shoes. Those are still the same shoes from season one. They're falling apart. The laces have broken so many times, they're barely holding on, but I will not change them.”

Rue’s relapse is one of the second season’s more challenging plotlines, with Zendaya pouring everything into her performance. In any given episode, she can enlarge the character with rage, fear and hysteria before shrinking her into ambivalence and bitterness, and over the course of eight episodes, the plotline finds her at her lowest. “It was interesting having to deal with the darker points of Rue's withdrawal, and when she hits rock bottom, it's very difficult,” says Zendaya. “But we have an incredible team of hair and makeup that assisted me in that. I would like to say that there was a lot of makeup added, but honestly, not that much. I can look rough when needed naturally, and that's okay.”

Dominic Fike, a singer-songwriter who is a new addition to Euphoria’s cast, became very familiar with the hair and makeup team. 

“I had to sit in a chair for two hours. I have a bunch of tattoos, and they had to cover every single one except for these (two face tattoos). So I got to know them really well over in makeup. I actually received a cactus from a lady who did my tattoos every day.” As for the costume department, well… “My outfits were all my clothing. Like, they just took my closet. They took my pants, they kept all my shit. I missed it so much.”

Hunter Schafer, who plays Jules, adds: “Heidi is a super collaborative costume designer, which has been amazing from season one, even. I think she really cares a lot about all the actors' perspectives and opinions on how their characters should appear and how it should feel. Without a doubt, it's a piece of the storytelling. It's super collaborative.” 

As the second season of Euphoria digs deeper into the messy teenage realities of these beloved characters, the performers are pushed to new extremes. It’s part of what makes the show so compelling: even as the characters make the most unwise and disastrous decisions – the exact kind of decisions we all made as teenagers – your attention and empathy is continually held by countless luminous performances.

“It's so fun to play characters that challenge you as an actor,” says Sydney Sweeney, who plays Cassie. “I think all of us were able to have experiences through our characters that pushed us deeper and deeper into the psyche, and being able to go to different places that we may have not have gone to, or we experienced a little bit of it, and then took it to a deeper level. It’s an art, and we get to explore that more.”

“I think people like the show because they can relate to that sort of cringe, 'Oh my god, what are they doing?'” says Maude Apatow, who plays Lexi. “Everyone sort of looks back at their high school, or at least I do, thinking, 'Oh god, I was such such a nightmare. This is so embarrassing.' I think that's one of the things that feels really real about the show, because teenagers do make some crazy choices sometimes.”

• Euphoria season two screens weekly on Neon/Sky Go