Liu on Southland.
Everett Collection

Playing Woo was a “big deal,” says Liu, opening doors in terms of popular culture, but her ascent to fame was a slow trajectory. Though she’s transcended “typecast” roles — Watson being Exhibit A — she doesn’t consider herself a trailblazer­ for other Asian-American actresses.

“It wasn’t about being a pioneer; it was about survival,” she says of her early days. “I wanted to be able to pay the rent and feed my passion. Individual choices have led me to where I am now, in addition to a whole team of people I have in place who helped me make those choices. Without them, you could get lost on the way and make decisions that could be damaging.”

The decision to make Watson a woman started out as a joke, but one Doherty found intriguing. During research for the show, he came across psychological assessments written by Sherlock experts, one of which suggested he had an aversion to women. “I thought, ‘What would make Holmes crazier than if you take the figurative rock of Watson and make that character a woman?’ ” he recalls. “I was intrigued by that dynamic and wondered if we could pull it off without coming at it from a romantic angle. In so many respects, it’s too easy to turn this into a romance. We could do that in a heartbeat — Lucy and Jonny have incredible chemistry as Sherlock and Watson.”

When asked about Miller, Liu’s face lights with affection. “Jonny’s great,” she says. “I love working with him. He’s so committed to the craft, and his dedication is off the charts. He’s just funny and lovely to be around, and it feels so lucky that we have this pairing.”

In preparing for the role, Liu downloaded the canonical novels and short stories of Sir Arthur Conan Doyle onto her Kindle, noting that in all but a few books, Watson narrates the duo’s exploits. Liu and Doherty decided to forgo TV and film adaptations and the occasional portrayal of Watson as a foil or fool. As such, Liu reclaims — despite her gender and ethnicity — the character as Doyle intended when he wrote his first Sherlock Holmes escapade, A Study in Scarlet, in 1886.

“In the literature, [Watson] was someone who was incredibly observant and a very close partner and confidant,” she says. “They really had something special.”