Everyone was watching Masi Oka, so the actor weighed his words carefully, measuring the worth of each syllable against its potential to evoke surprise.

Each time the director called for action on a cramped set for a morgue office of "Hawaii Five-0," Oka served as a bridge between realism and comic relief. As Dr. Max Bergman, the show’s socially challenged, oddball medical examiner, Oka aims to be unpredictable even as he delivers facts crucial to the police procedural.

"You OK with me playing with the role?" Oka asked guest director Jeff Hunt, who watched the actor’s scene with the show’s marquee man, Alex O’Loughlin.

And with that the bookish, bespectacled Bergman grabbed the spotlight from the brawny Steve McGarrett. Through several takes, Oka’s character wagged his finger at the "Five-0" star, got indignant and finally shouted "stop" so loud that cheers erupted when Hunt yelled "cut."

"I try to come up with three choices all the time," Oka said during a break at the "Five-0" production studio CBS created at the old Honolulu Advertiser building. "One of them is going to work, and you never know what will be a hit in the editing room."

Surprise has become the calling card for Oka in this second season of "Five-0." Although his character was introduced last year, CBS expanded the role during the show’s summer hiatus, and ever since, Oka has delivered laughs and revelations about the eccentric Bergman.

"It’s no fun if there is no mystery," Oka said. "I don’t want anyone to have figured out Max. Sure, he seems like a big geek. But all of a sudden, wow, he does sky diving. Wow, he drives monster trucks. Things you don’t expect."

The unexpected is an understatement. Oka pitched a lot of ideas to the show’s writers, including a musical episode patterned after Fox’s "Glee," he said. No word on where that idea is going.

"One thing they did like was the idea of Max dancing, possibly," Oka said. "So you might see a little bit of dirty dancing from Max."

The 36-year-old Oka was already a popular actor when "Five-0" brought him on board. He had won acclaim for his role as the time-traveling, time-stopping Hiro Nakamura on NBC’s "Heroes."

His "Five-0" character was in the original series — he was played by Al Eben — but like everything about the rebooted "Five-0," the new Bergman was pumped up. "Five-0" kept the medical examiner’s original name as an homage, and Oka said that at some point the show will explain why a guy of Asian descent has a Jewish surname (he was adopted).

FROM THE beginning, when the show’s regulars found his character playing a piano in the morgue, Masi put his acting stamp on every scene.

"My job is to heighten it, and everyone else’s job is to keep me in line — to make sure I don’t go too big," he said.

Paul Zbyszewski, one of the "Five-0" executive producers, said Oka can make him see a character in a whole new light.

"It is an intangible thing that you can’t put your finger on until you meet him and see him perform a scene," Zbyszewski said. "This is someone who can take something from the page that is dry and minimal and make it fun to watch. That is a rare quality."

Lines like that — what actors call "expositional" dialogue because it explains something central to the plot — are not easy to say, especially when the material is heavy on science or medical jargon.

"In the beginning of the show, there’s a lot of explaining — complicated cases and complicated evidence," said actor Scott Caan, who plays Detective Danno Williams. "It is sort of difficult to do, and I think Masi is really, really good at it. He can take expositional dialogue and make it interesting and funny."

The alternative is boredom, Oka said.

"You have to make it exciting," he said. "Not only for the audience, but for yourself. It’s fun when you can play."

Part of the charm Oka creates when the cameras roll comes from the halting speech pattern he’s given Bergman. Oka drew it from his own life. When he was a student at Brown University, where he earned degrees in mathematics and computer science, he had professors who talked just like that.

But Oka delivers his own eccentricity as well.

"I think with any kind of acting, particularly in TV, there is always going to be a piece of yourself in every character that you play," he said. "So it’s about taking that one quirk in yourself and then heightening it."

And the piece of Oka that lives in Bergman?

"I’m pretty much a perfectionist," Oka said. "I like to make sure things are done right. When I play games, in particular, I am a completionist."

When it’s time to step into character, to bring Bergman’s drive to life, Oka mines that vein — until it’s time for a surprise.

"He has this fixation for the truth and for justice," Oka said. "That’s the justification I gave to him. Hopefully he doesn’t just like to play with dead things."