Nathan Fillion and Stana Katic Nathan Fillion and Stana Katic

As the saying goes, you can't unring a bell. So, can you unspeak the words "I love you"?

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Also standing in the way of Castle and Beckett's possible love connection is a decrease in face time, now that new Victoria "Iron" Gates (Penny Johnson Jerald) has assumed command of the 12th Precinct and promptly kicked Castle out.

"He's not used to women being around him that aren't disarmed by him immediately," Fillion says. "Women love him, and when they don't, he takes it really hard. ... She won't give him half a chance. Even when he deserves credit, she will not give it to him. That really bothers him, and it's going to be a continuing battle."

But the true obstacle preventing a Castle-Beckett hookup is secrecy, as both Beckett and Castle will be forced to hide significant information from each other at the beginning of the season.

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