Heartstopper star Joe Locke didn't know the secret identity of his Agatha All Along character until halfway through his six-month audition process

Upcoming Marvel TV show Agatha All Along will see WandaVision’s breakout star Agatha Harkness, portrayed by a returning Kathryn Hahn, set off on a journey along the Witches’ Road in an effort to reclaim her power. However, she’s not alone, as Harkness has to assemble a coven of witches to take on the various trials the road presents.

Among the fresh faces is Heartstopper star Joe Locke’s mysterious bewitched boy named only as 'Teen'. Currently not much is known about the newcomer who is wrapped up in mystery, with fans speculating that he may be none other than Wanda’s 'imaginary' son Billy, a.k.a. superhero Wiccan in the Marvel comics. So far the actor has been giving cryptic responses when asked about his character’s true identity, recently telling Total Film magazine that "we’ll find out" whilst on the Witches’ Road.

But when did Locke himself discover who Teen really is? Sitting down recently with GamesRadar+ and the Inside Total Film podcast, the actor discussed the lengthy process to get the coveted role, which involved seven to nine auditions. At each one, Marvel Studios would tell Locke something new and exciting about Teen, which would make him more determined to get the part.

As Locke explains: "It was either seven, eight, or nine auditions - I didn’t actually count them. But it was a lot of auditions. It was over a six month period so it wasn’t too bad. Every audition I’d get further in and they would tell me more about the character or they would send me a script, so by the end of it I was like if I don’t get this part, I was so invested, I’d be so upset if I didn’t get it."

It was just over halfway through this process that Locke was told who exactly Teen was, the big secret of the upcoming show, which was thrilling for him to discover: "I was very excited. They told me pretty early on at audition four or five, they didn’t trust me before then… I feel like I’m saying too much."

He’s still clearly holding his cards pretty close to his chest then, with Locke realizing that if he lets anything slip he will ruin the big surprise Marvel has been building to. The fan theories online are already rife, even before the show itself has started on Disney Plus, but that anticipation will just increase and increase. 

Locke admits that he has been having fun reading some of these theories, concluding: "I read some of it but I try not to look at too much online because if you look at too much you always find negative things. But I think what’s so great about Marvel is the ability for fans to have theories about different things. And especially with a TV series, as every week people will have new theories and thoughts. One of the great things about Marvel is its secrets and it’s also great to know its secrets [laughs]."

Agatha All Along debuts with a double episode premiere via Disney Plus on September 18 in the US and September 19 in the UK. You can listen to our full interview with Locke in next week's episode of the Inside Total Film podcast.

For more from the world of the MCU, check out our guides to all the upcoming Marvel movies and shows. as well as how to watch the Marvel movies in order and what to watch to before Agatha All Along.