The Prime Video series "Young Sherlock," directed by Guy Ritchie and showrun by Matthew Parkhill, delves into the formative years of Sherlock Holmes, portrayed by Hero Fiennes Tiffin, before he fully embodies the renowned detective. The series introduces an intriguing dynamic as Holmes befriends Oxford student James Moriarty (Dónal Finn), setting the stage for a relationship that deviates significantly from traditional portrayals. While Holmes adheres to a strict moral code, Moriarty's ethics are more fluid, driven by amusement or necessity. Their globe-trotting murder investigation to uncover a conspiracy is further complicated by intense Holmes family drama, leading Sherlock to question deeply held beliefs and discover surprising secrets about his newfound best friend.

Hero Fiennes Tiffin, reflecting on his role, shared insights into this youthful version of Sherlock. He noted the character's "smart ass" demeanor, but highlighted his current inability to defend himself, a stark contrast to the skilled combatant depicted in Sir Arthur Conan Doyle's works and later adaptations. Fiennes Tiffin humorously recalled expecting to emulate Robert Downey Jr.'s choreographed fight scenes but quickly realized his Sherlock would endure multiple punches to the face. He embraced this vulnerability, understanding it as a "beautiful flaw" essential for illustrating Sherlock's journey towards becoming the iconic detective, demonstrating that he still has "a long way to go" in his development.

A particularly unique aspect of "Young Sherlock" is the friendship between Holmes and Moriarty, a concept Fiennes Tiffin initially found "jarring." However, he came to appreciate its believability, noting that both characters are exceptionally brilliant, even among Oxford's bright minds, making their bond understandable. This friendship, Fiennes Tiffin suggests, adds a "beautifully painful layer" to their eventual rivalry, implying that Sherlock might intentionally omit their past friendship when recounting Moriarty to Watson. The most enjoyable moments for viewers, according to Fiennes Tiffin, are their high-stakes scenes where they can't resist one-upping and insulting each other, even when their freedom is at risk. He cited an undercover scene as policemen and a hat shop incident where Sherlock cleverly undermines Moriarty's flirtatious attempts as prime examples of their dynamic.

Fiennes Tiffin also found the scene where Moriarty flirts with Sherlock's mother, Natascha McElhone's character, particularly memorable and hilarious to play, acknowledging the incredible chemistry and talent of Dónal Finn and Natascha McElhone. He admitted to feeling Sherlock's discomfort in that "unfair" yet comedic situation. The casting choice for Sherlock's father, Silas Holmes, was also a significant point of discussion, with Joseph Fiennes, Hero's uncle, taking on the role. Hero confirmed it wasn't his idea but expressed immense excitement at the opportunity to work with his uncle. He felt the timing was perfect, having gained sufficient acting experience, and found the uncle-nephew playing father-son dynamic to be a "luxury." He recounted a touching moment during their first scene, where Sherlock sees his long-absent father, and Hero experienced a personal connection to seeing his uncle Joe, feeling a strong desire to impress and make him proud.

Regarding the mysterious key Sherlock finds, Fiennes Tiffin does not know what it unlocks but appreciates its symbolic power as a cliffhanger and a metaphor for a "continued journey." He praises showrunner Matthew Parkhill for his genius in balancing resolved plotlines with tantalizing new mysteries at the end of each episode and season. The decision for Sherlock to keep the key a secret from Moriarty, Fiennes Tiffin believes, stems from Sherlock's strong moral compass. Despite valuing Moriarty as a good friend who offers support and helps Sherlock see truths clouded by emotional family ties, Sherlock's inherent drive for justice and truth makes him aware that he might one day have to "cut Moriarty off" if their paths diverge too far morally. Fiennes Tiffin profoundly felt the sadness of playing a character so driven by these internal conflicts.

Ultimately, Fiennes Tiffin expressed gratitude for the "unexpected" nature of the series, which keeps viewers engaged despite the numerous Sherlock Holmes retellings. He attributes this success to Matthew Parkhill's incredible writing and the exceptional cast assembled by casting directors Rory Okey and Dan Hubbard, as well as the talented heads of departments. He considers himself fortunate to portray such an iconic character alongside his favorite directors and a wealth of talent across all aspects of production. "Young Sherlock" is currently available for streaming on Prime Video.