BBC 'Sherlock' Season 4 Air Date & Premiere: Actor Benedict Cumberbatch Reveals Sherlock's Background, Weakness

"Sherlock" actor Benedict Cumberbatch sat with Eric Deggans of NPR, and the two chatted about the action-drama series, the show's fans and his transformation into Sir Arthur Conan Doyle's most famous character, Holmes.

During his interview, the newly engaged Cumberbatch was aware of fans standing outside of the hotel. He communicated with his assistants, asking them to inform fans that he would stop by to see them soon, showing that concern comes natural to the international star.

"Sherlock" fans have a long wait ahead of them, having to wait more than a year for the single special episode that will air next Christmas, and then they must wait even longer for the upcoming three-episode season that will air in early 2016. To tide them over, BBC released a new DVD and Blu-ray box set early this week, which contains all three seasons of the dark and fantastic series, as well as outtakes, new commentaries, interviews and an collectible resin mini-busts, which the depicting the series' two male leads. With the new release, fans will learn more about the mysterious detective's background.

"You find out about Sherlock's background," the actor said. "You find out that he comes from a truly stable home. It was a gesture in the first episode, but you see that in practice in the third. You see that, as a boy he was deeply insecure -- it begins as a taunt [from his older brother, Mycroft] ... and that comes back to haunt him and he feels like a child. He's reduced to feeling like a child."

Cumberbatch speculated that those storylines derived from conversations during in the first season's production with series' producer Steven Moffat.

"Immediately as an actor I wanted to understand who [Sherlock] was, what his parents were," he said. "These were questions I asked. ... I wanted to understand. [Moffat] was just talking about, 'Can't this guy just be good at what he does and he's your age and he looks like you and he's doing his thing?' And I went, 'No, no, Steven. There's a process I've got to go through. I've got to understand how I became this person.' "

However, Cumberbatch said fans probably won't get all the answers: "I can't just sort of float onto set with a whole bunch of mannerisms and hope it sort of comes off. You have to ground it in some sort of reality, otherwise you get found out as things sort of evolve."

Cumberbatch also insisted on creating a weakness for Sherlock, an inability to connect with people, which Moffatt resisted.

"And [Moffat] said, 'But can't he just be really good? Can't he just be good at it? Why does he have to have flaw or an Achilles' heel?'" the actor said. "Because I said, you know, 'Where's his weakness?' Because no human being doesn't [have one]. And however much [Sherlock] tries to convince himself he's not human, he is."

Early conversations sparked ideas and shaped the show's third season, which featured a look at Sherlock's parents (played by the star's real mother and father) and an investigation into his unique personality. This was revealed in a climactic scene with the episode's villain, where the deductive detective declared himself "a high functioning sociopath."

To learn what else was said in the interview, find the interview here.