From comedy to crime: Randall Park talks surprising role as Professor Moriarty in 'Watson'

Warning: Spoilers ahead from the premiere episode of CBS drama "Watson."

Even the legendarily brilliant detective Sherlock Holmes would never have seen this Professor Moriarty coming.

"Watson" revealed the surprise archvillain at the end of CBS' Sunday premiere of the medical mystery in the Sherlock Holmes universe, as told through Dr. John Watson (Morris Chestnut). The series' Moriarty is played by Randall Park, and he's wearing a polyester polo shirt.

The casting of the infamous criminal mastermind in casual work attire was startling even for Park, 50, the comedic actor best known as the mild-mannered dad in six seasons of ABC comedy "Fresh Off the Boat." He also played a cheerfully underachieving video store manager in Netflix's "Blockbuster," requiring a different polyester polo shirt).

"I'm known for playing amiable, nice guys. So it was a surprise to get the call. A welcome surprise," Park exclusively told USA TODAY of his evil turn. "The idea of playing a villain is thrilling to me."

Park has played baddies before: He was North Korean dictator Kim Jong-un in the infamous 2014 comedy "The Interview." But that was for dark laughs. Even Park's Marvel series "WandaVision" character, by-the-book FBI Agent Jimmy Woo, is played with comedic deadpan. But Moriarty is straight-up serious.

"They wanted someone who can come off as kind of a regular everyday guy," Park said. "But is this regular guy really a dangerous, psychotic supervillain?"

How is Randall Park's Moriarty unveiled in 'Watson'?

Moriarty and Holmes were both supposed to be dead in "Watson" after a violent, series-opening grapple that ended with a gunshot and a double plunge into an icy Swiss waterfall. Watson dove in to save his closest friend but suffered a debilitating blow to the head from a rock. After recovering, Watson began leading Pittsburgh's Holmes Clinic, specializing in curing rare disorders, thanks to his former companion's generous will.

But Moriarty is alive, coming into focus unobtrusively in the series premiere's final moments while sitting on Pittsburgh's famed Duquesne Incline cable car. Watson's right-hand man, Shinwell Johnson (Ritchie Coster), is even surprised to find the easily overlooked villain in the white polo with the mysterious logo "Always & Everywhere."

"I was expecting someone... different," Shinwell said, handing over a case of clinic DNA samples. Moriarty monologues about "a germ (that) might even write its name in history" in Pittsburgh before exiting with a wicked smile.

"That affability disguises something much more sinister," said "Watson" executive producer and writer Craig Sweeny. "He's the guy who could fix your washing machine or your disc drive. Great performers were interested in this part. But Randall was entirely different; that was attractive."

Who is Moriarty in the Sherlock Holmes universe?

Professor James Moriarty is Holmes' formidable enemy in the famed Sir Arthur Conan Doyle detective novels, described as walking "in a curiously reptilian fashion." Sir Laurence Olivier played him in the 1976 movie "The Seven-Per-Cent Solution." Andrew Scott earned raves as nattily dressed Jim Moriarty in the Benedict Cumberbatch-led 2010-17 BBC series "Sherlock."

Sweeny kept the character under wraps, referring to him only as "Pittsburgh Dad" when writing the script and even on the sign adorning Park's trailer on the Vancouver set.

"It wasn't like Marvel-series secrecy where we had to sign NDAs," Park said. But keeping the secret helped him find the character each day. "Every time I looked at the call sheet and saw 'Pittsburgh Dad,' it was like, 'OK, assignment understood.'"

Moriarty will appear throughout the "Watson" season in different but office-suitable apparel. "He's really not a fashion guy," Park said. He promises a Watson-Moriarty faceoff by the end of the season. But even in episodes when he's not on screen, Moriarty's underlings do his bidding, and his evil presence is felt. "Just like the shirt says, he's always there, always watching," Park said.

Chestnut is pleased with the addition of his "Watson" TV rival.

"In the last scene, you see that little smirk and the devious nature of Mr. Park," Chestnut said. "That is just a hint of the things to come."

This article originally appeared on USA TODAY: Randall Park talks surprising role as supervillain in 'Watson'