The ''Lost'' couple had some of the most explosive scenes of the season

By Dan Snierson
Updated November 14, 2008 at 05:00 AM EST

Once upon a time in the land of Lost, a boy named Jin married a girl named Sun. Alas, they did not live happily ever after: Jin grew distant; Sun became alienated. Then they boarded Oceanic Flight 815, and that didn’t go so well either. The Korean couple’s tenuous relationship played out for years as a nuanced romantic subplot that always felt a tad removed from the other stories on the cursed island.

Until season 4.

As Lost sharpened its focus with an impressive endgame launch (the producers persuaded ABC to wrap up the drama in 2010), it also supercharged the saga of Jin (Daniel Dae Kim) and Sun (Yunjin Kim) so that the story radiated intrigue, redemption, and heartbreak, and plugged them into the greater mythology of the island. ”We have a fan base, but it tended to be fans of romance,” says Daniel. ”The big question was ‘There’s a reason Jin and Sun are here. How important are they to the overall story?’ [Now] we’ve started seeing how we tie in.” Adds Yunjin with a chuckle, ”People say, ‘About time!’ And I say, ‘Damn right!”’

Over the course of the season, we witnessed Jin complete his metamorphosis into a compassionate spouse, forgiving a pregnant Sun for her pre-island affair and reaffirming his devotion to her. (”That spoke volumes about how far he’d come,” notes Daniel.) Yet Jin’s journey seemed to be cut short after he tried to help defuse a bomb on a boat that the castaways hoped would be their rescue. Meanwhile, in those ominous flash-forwards, we saw Sun give bittersweet birth without her husband by her side, visit Jin’s grave (could he possibly be alive? Tune in to season 5), and transform into a stone-cold International Woman of Business and Mystery.

But the image that still haunts Lost fans is Sun’s horrified reaction after watching Jin, trapped on the doomed freighter, attempt to frantically flag down the helicopter that Sun was in and…BOOM! For a master class on grief simulation, see Yunjin — whose screamfest was shot against a greenscreen — obliterate her vocal cords while begging the pilot to turn back. ”It was such a short scene…. I wasn’t expecting such a huge reaction to it,” she says. ”It was just me on stage, trying to find a spot on the floor, imagining Jin waving his arms and running to me. I was doing everything I could to make it real.” At that moment — like so many this season — everything came into focus.