'It's easy to romanticise toxicity' says star of film about step-siblings' romance

Scroll through TikTok for long enough and you'll find short films about fictional relationships, with painstaking fan edits, imagined future storylines, AI-generated posters and millions of comments debating them as if they're real.

This level of fandom has transformed young adult romance, often found in novels, into one of streaming's safest bets.

With #BookTok attracting around 80 million posts on TikTok and #romancebooks more than 6.5 million, platforms are now investing heavily in bestselling novels with passionate online audiences - before a single scene is filmed.

The latest entry into that booming genre is Your Fault: London.

A film based on the bestselling novels by Spanish author Mercedes Ron, it stars Asha Banks and Matthew Broome, who say they have been struck by the intensity of the franchise's existing fanbase.

"The fans are the reason the films are so successful," Banks tells the BBC. "The visibility of it and where it lives is so much on social media."

This film is the latest chapter in an unlikely success story that began not in Hollywood, but on the reading platform Wattpad, where the Argentine-born Spanish writer Ron first published the Culpables trilogy.

The books - called Culpa Mia, Culpa Tuya and Culpa Nuestra were all written before she was aged 20, and after launching on Wattpad, they went on to became bestsellers, and hugely popular with teenagers.

They were then adapted into a hugely successful series of Spanish-language films, simply titled Your Fault.

The English-language version of the story - Your Fault: London, story follows Noah, who moves to the capital city after her mother marries a wealthy businessman.

Noah falls for the businessman's son, Nick. The step-siblings' romance is tested by family tensions, buried secrets and their own impulsive decisions.

The films were number one in more than 170 countries at launch, with over 90% of viewers coming from outside Spain, Amazon said in February.

The middle film picks up as Noah starts Oxford University and Nick focuses on his career, with new relationships and old conflicts threatening to pull them apart.

Banks promises "a lot of drama", while Broome says audiences will constantly be torn between the pair.

"You'll be agreeing with one character and then think, 'Oh no, the other one is right.'"

The English-language version has a new cast and a London backdrop.

Banks, 22, thought "it was interesting they were doing an English version so quickly".

"But ultimately people love the story and resonated with it so much and that's why it was such a success. So why not?

"It's so much fun, it's addictive and entertaining and it's great to bring it to a new audience."

Broome agrees and says the rapid turnaround "emphasises the power of Mercedes Ron and her books".

'People will definitely watch it'

For the actors, the most unusual part of the experience has been joining a story that already had millions of passionate readers and viewers.

"You have mega fans of all of these BookTok books," Broome, 25, says.

"You're making something with an added level of excitement because you know people are going to watch it. We don't know how they'll receive it, but they will definitely watch it."

Similarly, The Guardian called the original Spanish films "a bizarre and wooden step-sibling romance".

But fans of the books and Spanish films have embraced it.

BookTok creator Tia Saunders, 22, says the films are "phenomenal and amazing adaptation".

"I love the forbidden love element and the casting is brilliant."

Broome and Banks are grateful for the fans but admit that sometimes the online attention can also be overwhelming.

Broome says he regularly comes across AI-generated images imagining the pair's future together "which is kind of crazy".

"I'll see a poster and I think, 'Wow, we've released a poster' but it's actually just a fan creating one."

Having each other has helped the young actors navigate the attention, and Broome explains that "as soon we're overwhelmed we just talk to each other".

He adds that because much of the fandom exists online, "if you put your phone down you can disconnect from it".

The pair deliberately avoided watching the Spanish version, wanting to develop their own interpretations of the characters.

They only watched the originals after filming had wrapped and "it was lovely because we watched it together and our version was done so we couldn't compare," Banks says.

Broome believes the British adaptation stands apart because "our dynamic is completely different" and Banks adds that the change in setting gives the story a new identity.

The series has sparked debate over whether it romanticises toxic relationships, with Noah and Nick's romance often marked by jealousy, secrecy and conflict.

Broome argues the films instead show the consequences of those behaviours.

"You see it go wrong with Noah and Nick and you see the bad toxic traits that fall out of that. Then you see what you need to resolve the conflict, which is healthy communication."

Banks says they were conscious of portraying two young people still figuring themselves out, rather than presenting their relationship as an ideal.

"It's so easy to romanticise toxicity, and their relationship is full of that, but you are watching them work that out themselves alongside the audience," she says.

The actress adds that one of the aspects she most enjoyed was Noah's resilience, saying "it was so lovely for me to play a strong young female character and I hope that's reflected on the screen".

Your Fault: London is available to watch on Prime Video now.