The Castle family will be growing this fall.

New executive producers and co-showrunners Alexi Hawkey and Terence Paul Winter tell that a new bundle of joy will cause some headaches at the 12th Precinct, particularly for Ryan (Seamus Dever) and Esposito (Jon Huertas). "We have some exciting news for the Ryan family: They're expecting another kid," Winter says. "Ultimately, that's going to make Ryan even more paranoid and more excited about trying to make more money. When he sees Beckett rising up in the ranks, the boys realize it's time for them to start looking at their futures, which is going to create some tension and conflict between them."

It remains to be seen if Ryan's new offspring will deter Hawley and Winter from having Castle (Nathan Fillion) and Beckett (Stana Katic) pursue parenthood this season. Whatever they decide on that front, the producers want to make one thing clear: Castle's new partner Hayley (Toks Olagundoye) is not a threat to Castleand Beckett's marriage. "That was never our intention," Hawley says of introducing the new character. "It's not going to happen."

In fact, whatever challenges the couple may face this season, the producers are keen on furthering the core duo's relationship. "It's always been about the Castle-Beckett love story. That's steeped in the DNA of the show, and that's what it will always be," Winter says. "Now, it's about exploring the next evolution of it. How do we deepen that love story? What challenges can we put their way that can put their romance at a much higher, different place?"

Castle returns Monday, Sept. 21 at 10/9c on ABC.