By Tom Gliatto Cynthia Wang
October 30, 2006 12:00 PM

“I love the tension-building,” says Elizabeth Mitchell, 36, who’s got an unexpectedly sexy warden-prisoner vibe goin’ with Matthew Fox in her role as Juliet, the Other who keeps tabs on his cell and gives him penetrating looks. “She’s kind, yet very tough,” says the actress (best known as Laura Innes’s lover on ER). She doesn’t know her character’s full story yet, but she just received the script with Juliet’s big flashback. So …? “Ooh, it’s intriguing!”