When Gloria Reuben was recruited for CBS's upcoming CIA thriller The Agency (airing Thursdays at 10 pm/ET beginning Sept. 20), she knew full well that the network planned to schedule the show opposite her alma mater, NBC's still-potent ER. But incurring the wrath of her former colleagues was hardly her primary concern. "I thought, 'They must really feel confident about this show,'" she laughs to TV Guide Online.

Well, Tiffany execs no doubt feel more secure about The Agency's chances now that they have stolen one of the medical drama's most valuable alums. Surely, Reuben — who left ER in 1999 to sing back-up for Tina Turner on the pop diva's world tour — feels a smidgen of guilt about going to work for the competition, right? "I never really thought about it that way," she admits. "I'm certainly not forbidden to do any show Thursday nights at 10 o'clock for the rest of my life.

"Hopefully there wouldn't be any resentment because it's been a while," adds the 37-year-old actress, who received two Emmy nods for her ER role as HIV-positive PA Jeanne Boulet. "I know that in Hollywood there tends to be this undercurrent of competition and backstabbing, [but] I don't look at things that way. I certainly didn't look at this as an opportunity to get back at anyone."

For his part, ER executive producer John Wells says he's not walking around with a scalpel sticking out of his back. In fact, he tells TV Guide Online that even if Reuben was interested in checking into ER again, he'd be hard-pressed to conjure up a comeback scenario. "I thought it would be difficult — in a different way than it was for [returning castmate] Sherry Stringfield — for her character to come back even if Gloria had called, because of the way we left it," concedes the writer-producer, who had Jeanne move away to start a new life with her husband and child. "She didn't leave as clean as Sherry did."

Speaking of exit strategies, the folks at The Agency may want to start brainstorming ways of writing out Reuben's CIA operative, Lisa Fabrizzi, now. The East Coast-based thesp — leery of relocating to Los Angeles (where The Agency is shot) — only agreed to do six episodes. "I'm married and I can't just move," she sighs. "It's a quality of life thing. I prefer to live on the East Coast. It's more suited to my nature."

That said, Reuben realizes a groundbreaking character like Lisa is a rarity on TV, and as a result, she's talking to execs about possibly extending her run. "When was the last time you saw a mulatto female being a leader in a government agency?" she marvels. "I don't think I've ever seen it before."

And what about her singing ambitions? They're still there. Actually, spending 10 months harmonizing in Turner's legendary shadow only reinforced something Reuben has long believed: "I need to be [the one] up front," she says, adding with a wink: "I'm working on it."