Young Sherlock: How Prequel Series Changes Dynamic Between Detective And Nemesis Moriarty Into 'Incredible Friendship'

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Fiennes Tiffin becomes the latest actor to play Sherlock Holmes in Amazon Prime Video's upcoming series. Young Sherlock will follow the detective's first-ever murder mystery case during the 1870s in an adventure spanning the world. Get ready to see one big change in the 2026 series. Sherlock and his future nemesis, James Moriarty (Dónal Finn), are great friends at Oxford. Here's how the show changes their dynamic.

Young Sherlock changes foe to friend with Moriarty

In an interview with Entertainment Weekly, showrunner Matthew Parkhill shared that the show makes the future enemies first in this origin story. It will explain more why the two hate each other so much in the future. He shared, "I always imagined what it would be like: How did they end up such mortal enemies? And I always thought, what if he had this incredible friendship?"

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He added, "You kind of get two origin stories for the price of one. Moriarty gets in hot water as well. And I think if these two hadn't met, it's sort of like a pinball and a pinball machine, if they hadn't met, Sherlock wouldn't have become the Sherlock that we know, and Moriarty wouldn't have become Moriarty." ALSO READ: Guy Ritchie’s Young Sherlock Series Adds THIS Actor As Main Nemesis MoriartyStar Hero Fiennes Tiffin teased that the show will introduce elements from the classic Sir Arthur Conan Doyle stories in a clever way. He said, "This is what makes our show so fun is that people know where they're going to go, but we're not going to get there yet. And it's all about teasing the audience with and giving them just enough to be fed, but stay hungry when it comes to Sherlock and Moriarty's relationship or Sherlock's skills as a detective or in fighting. And I think that's going to be really fun for people to watch."

More about Young Sherlock

Other key roles in the show are brother Mycroft Holmes (Max Irons), father Silas Holmes (Fiennes Tiffin's uncle, Joseph Fiennes), and mother Cordelia Holmes (Natascha McElhone) as the sleuth's mother. Zine Tseng plays enigmatic Chinese Princess Gulun Shou’an, while Colin Firth plays Oxford's Sir Bucephalus Hodge. Parkhill also revealed that the show will not touch anything after the first Sir Arthur Conan Doyle story. But there are many Easter eggs in the Amazon Prime Video show that hint at Sherlock's future for fans to find.