'Sweetheart' star Sophia Di Martino is no longer our best kept acting secret after 'Loki' (exclusive)

For years, Sophia Di Martino was one of our best kept acting secrets. A reliably radiant presence in such shows as Flowers and Mount Pleasant and movies like Yesterday and The Darkest Universe, she found herself thrust into the media spotlight earlier this year when she debuted as Sylvie, aka ‘Female Loki’, in Loki, Disney+’s uber-hyped series based around the impish supervillain.

So, if you’re used to seeing this 37-year-old Nottingham native gussied up as a Norse god and kicking Tom Hiddleston’s ass amid a blizzard of CGI, then you’ll be in for a shock when you see her in Sweetheart.

A low-budget, defiantly British coming-of-age tale that’s as sweethearted as its title, it stars Di Martino as Lucy, the older sister of 17-year-old AJ (newcomer Nell Barlow) who, having reluctantly come on holiday with her perma-squabbling family, meets her dream girl, holiday park lifeguard Isla (Ella-Rae Smith).

Read more: How Loki sets up a second season

“Working on a film like this, it's a much smaller crew,” Di Martino tells Yahoo. “You get to know everyone on that set. And we were also living in the holiday park where we filmed so we were all neighbours. We'd pop round to each others’ caravans for a cup of tea. It’s a much more intimate experience and lovely because of it.”

Although she’s now an integral part of the Marvel Cinematic Universe (scuttlebutt has it she’ll be cameoing as Sylvie in Sam Raimi’s Doctor Strange And The Multiverse Of Madness, but the Marvel Police will likely swoop in if she confirms that one), Di Martino is keen to balance the gargantuan special effects spectaculars with more modest indie fare.

A keen filmmaker herself (her second short, Scrubber, is currently doing the rounds at festivals before, she hopes, it will find a home online), she says it’s only through the independent scene that stories like AJ’s can be told.

“To see a lesbian character at the centre of her own movie is great,” she enthuses. “It's not about coming out, it's about her summer and she has a happy ending, and that's actually very rare. I love working on projects like that, as well as all the big stuff. On this film, it was a really lovely experience to work with some of my mates.”

Di Martino has history with Sweetheart director Marley Morrison, having featured in her award-winning 2017 short Baby Gravy, but it was her first time working with Nell Barlow. The twentysomething actor only graduated two years before Sweetheart lensed and Di Martino is full of praise for her young co-star.

“I was blown away by how incredible she is, and how little experience she's had,” she beams. “And also how confident she was in front of the camera and how dedicated she was to the role and making the film as good as she could. I just think she's brilliant. Off-camera, I actually felt really sort of protective and maternal over her and I'm always like, ‘I'm so proud of you!’ So I’m not as horrible as Lucy is to her.”

When Sophia filmed Loki she had recently had her first baby (she’s currently expecting her second), which necessitated a few subtle modifications to her costume. By the time she was on set for Sweetheart, however, her bump was so immense that her pregnancy was written into the script.

"It’s little (big) things like this,” she wrote on Instagram alongside a photo of Sylvie’s baby-friendly outfit, “that made it possible for me to do my job and be a parent.”

Being one of the most important new characters in the Marvel Cinematic Universe (it’s Sylvie who has, in effect, laid the groundwork for Phase 4 of the MCU by unleashing the multiverse), Sophia has seen her star rocket these past months. So, how has life changed since becoming the co-lead in one of Disney+’s most watched TV shows?

“It's been so lovely to see all of the reactions and the feedback,” she says, “and finding out about the fans and how much it's inspired them, and then seeing all of the art and the edits that people are creating, it's quite overwhelming. But honestly, my personal life is very similar. I still feel like the same person, and I'm still gonna have the same thing for lunch that I had before, you know?”

Though she won’t be drawn on whether she’ll be guesting in any future Marvel movies, we know for sure she’s inked in for Loki’s now-confirmed second season. Asked about the progress of series two, however, and she admits that she’s “in the dark” about it.

“I’ll probably get updates at some point,” she smiles. “So we'll just have to wait and see…”

Seeing as she worked through her last pregnancy, don’t expect Sophia Di Martino to scrub out her work calendar just because she’s with child again. What those jobs are, however, she’s a little coy on. (Is that the Marvel cops we can hear circling?)

“Well, there’s nothing that I can sort of declare right now,” she teases. “But there are exciting things around the corner!”

​​Sweetheart is released in cinemas on 24 September. Watch the trailer below.