Taraji P. Henson, Jim Caviezel

Over the last few episodes, CBS' Person of Interest has done something rather, well, interesting.

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The hit freshman procedural has taken Taraji P. Henson's Detective Carter — the cop who spent the first half of the season hot on the trail of vigilantes Reese (Jim Caviezel) and Finch (Michael Emerson) — and turned her into the high-tech duo's partner in vigilantism. Creator and executive producer Jonathan Nolan acknowledges that, at the request of CBS, the twist has happened faster than he originally intended, but he insists it was always in the back of his mind.

"The pitch from the very beginning with this character was that you'd start with a little bit of Tommy Lee Jones from The Fugitive, and you'd wind up with a character closer spiritually to Commissioner Gordon," Nolan tells TVGuide.com. "We didn't want these relationships to be ready-formed from the pilot. The network gave us a great deal of latitude in terms of earning this relationship. But the plan is still unfolding."

Indeed, to this point, Carter only knows as much as Reese or Finch is willing to tell her about their little operation. Additionally, Carter has no idea that her fellow cop Fusco (Kevin Chapman) is also secretly feeding police information to Reese. Naturally, those types of secrets could quickly derail this new arrangement.

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"These relationships are not fixed," Nolan says. "There are no guarantees about any of these characters. Just because characters are allies now, doesn't mean they're going to remain allies."

Unlike Reese and Finch, who were always operating outside the law, Carter is a sworn officer, which makes her side job all the more tricky, not to mention dangerous. This is especially true in Thursday's episode (9/8c, CBS), which features the return of CIA Agent Mark Snow (Michael Kelly), the operative who shot Reese after Carter put him on Reese's trail. This time around, Snow may have just as many questions about Carter as he does about Reese.

"One of the fun dilemmas of our show is you have these people doing the right thing, but in unorthodox terms and illegal terms," Nolan says. "There are influences within her office, or various other law enforcement agencies, that are going to start to inquire as to what she knows. What sort of position [does] that put her in?"

Person of Interest airs Thursdays at 9/8c on CBS.