JYJ’s Kim Jae-joong and Z:EA’s Im Si-wan are working together on a drama for the first time, teaming up to play long-lost brothers in MBC’s upcoming “Triangle.”

Separated as children by unfortunate circumstances, Kim’s character Heo Young-dal takes to the streets as a petty thug while his younger sibling Yoon Yang-ha, played by Im, is adopted into a chaebol household to be groomed as the heir to a casino empire.

Their ill-fated paths converge on casino territory where both, unaware of their blood ties, fall for dealer Oh Jeong-hui, played by actress Baek Jin-hee, in what promises to become a high-stakes, soap-operatic love triangle.

At the press conference for the drama in Seoul on Wednesday, both Kim and Im displayed an easy camaraderie at odds with the sibling rivalry that is sure to unfold between their characters when the show starts airing next week. 

As the two popular hallyu stars sat down to discuss their new project with the press, both admitted to being a bit starstruck when they first met.

“It was really amazing,” Im, 25, said of how he felt when he finally got to meet Kim.

“I was in awe too,” Kim, 28, said. “When I first saw Im in real life, my initial impression was that he was really good-looking and pretty.”

The two singer-actors bonded over meals and drinks. Im recounted how he was surprised when Kim ordered some mackerel, rice and side dishes.

“I thought he wouldn’t eat at all,” Im said, adding that he had envisioned Kim as someone shrouded in an aura of mystery. “Then I saw him eating that mackerel and rice and he suddenly seemed very human. It was good.”

Now that the ice has been broken, both stars are ready to tackle their latest roles with gusto.

This will be Kim’s fourth and Im’s fifth television drama to date.

For Im, this represents his first full-length series.

“Up until now I have primarily played the younger version of the leads,” Im said, referring to past child roles in hit series like MBC’s “Moon Embracing the Sun” and KBS’ “Man From the Equator.”

Im admitted to being concerned about the toll all those long hours of filming would take on him, but displayed determination to do his utmost by immersing himself completely in his role as a jaded and lonely heir.

Im described his dark hero, Yoon Yang-ha, as someone that people would envy, not pity. “My character is blessed with everything,” he said.

Im said he reached deep to find the empathetic core of his character, the source of all that emotional emptiness. “He lost his brothers when he was young. His father isn’t really his father and doesn’t really treat him like his son. He treats him like an heir, someone he needs to groom to take over his business.”

Im added that this is fairly new, dark territory for him, a contrast to previous roles, where he often played warm-hearted, kind and sweet supporting leads.

“Im is like a clean slate. That is one of his charms,” “Triangle” director Yoo Cheol-yong said. “I think he displays strengths and merits that make him well suited for the role of the younger brother.”

Meanwhile, director Yoo said he cast Kim because despite the singer-actor’s “soft and sweet” demeanor, there was a certain “sharpness” in his eyes.

“It’s a completely different role from those he has played before,” Yoo said. “He is doing a great job.”

Costar Lee Bum-soo, who will be playing the older brother to both Kim’s and Im’s leads, praised Kim, having worked with him on MBC’s “Dr. Jin.”

“While filming ‘Dr. Jin,’ Kim was always humble, responsible and reliable,” said Lee.

Kim seems to take his acting very seriously ― so seriously, in fact, that when he saw he had a shirtless scene coming up, he deliberately lost weight and did not bulk up to stay true to his character.

“Then a week before filming the scene they told me they would like to see a bit more weight on me,” Kim said, explaining how he had to put on muscle within a very short amount of time.

As for the long hours, Kim is embracing the whole process.

“When you are not sleeping a lot, you get sort of hazy and out of focus. Yet that state of mind seems to be in sync with my character, Yong-dal, who is a brash, lazy, not-quite-all-together sort of guy.”

“Triangle” starts airing May 5 on Monday and Tuesday nights at 10 p.m. on MBC.

By Jean Oh (oh_jean@heraldcorp.com)