David Boreanaz, Emily Deschanel

Ever since the demise of Moonlighting, many television writers have had one great fear: Once their show's two romantic leads sleep together, the show will lose its tension and become lifeless.

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But Bones creator Hart Hanson — who faces that challenge as the show's seventh season premieres with Dr. Temperance Brennan (Emily Deschanel) pregnant with the child of her former will-they-won't-they partner Seeley Booth (David Boreanaz) — has found the opposite to be true.

"I feel like it re-energized the series," Hanson tells TVGuide.com. "I think it breathes new life into the franchise — into the story engine of Booth and Brennan. The reason we put them together is that it's just been so long. It had to happen. We just could not put it off anymore."

The trick, Hanson says, is finding drama to replace the sexual tension. Even though he and executive producer Stephen Nathan had planned for a Booth-Brennan hookup from the beginning of Season 6, it wasn't until Deschanel revealed she was pregnant that the duo landed on their new dynamic.

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"We knew we did not want them getting together and breaking up. We didn't want misunderstandings," Hanson says. "So, they're contending with a brand new relationship. 'How together are they?' is a question that needs answering. And how are they going to deal with having a child together? As we started banging out this season, it just gave us so many places to go with story."

Thursday's premiere finds the couple tired of splitting time between their respective homes and considering a more permanent cohabitation solution. Other bumps in the road could include the couple's differing views on religion, not to mention that Brennan learns the sex of the baby without even including Booth.

But Hanson says the drama won't be so trivial all season. "There are deeper places to go," he says. "What happens to the relationship between two people who share a child and love each other deeply? That's our journey this year. Where do they go next? And of course, the biggest question is, do they get married?"

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Booth's reaction to (or fear of) that question may be somewhat surprising, given his history. "I think it really is a peek into how Booth has progressed," Hanson says. "[He's] the man who keeps asking people to marry him, and they never say 'yes.' He's maybe learned to lay back a little bit."

Although Hanson says "motherhood opens up an emotional side that is not easy for [Brennan] to deny," Booth will also find himself in a very reflective state as he prepares to become a father again. "Booth has had a combative and difficult relationship with his father," Hanson says. "His father was abusive, and we have a story coming up with [Booth] and his grandfather, concerning his dad.  And it's just... having a kid, changes everything in your life. Everything is from a different perspective."

Not surprisingly, family will be a theme throughout the season. The show will explore the ups and downs of new parents Angela (Michaela Conlin) and Hodgins (TJ Thyne), as well as revisit the relationship between Cam (Tamara Taylor) and her teenage daughter. Plus, the Jeffersonian is adding a new squintern (Luke Kleintank) to its "family" after the death of Vincet Nigel-Murray (Ryan Cartwright) last season.

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But the show also remains focused on catching bad guys. This season will introduce a new tech-savvy villain (Andrew Leeds) who will stump both Brennan and Booth.

"I think he is a great amalgamation of high-tech and analog," Hanson says. "This serial killer flummoxes them both by swapping back and forth, and they have to combine their talents. It would be too creepy to say that it's like, 'What if Booth and Brennan's baby grew up to be a horrible serial killer?' But thematically they have to deal with two things this year that are a combination of the two of them. One's the baby, and the other is this big baddie."

And will the couple stop to consider that chasing killers might not be in the best long-term interest of Baby Bones? "That's exactly one of the arenas that we have to deal with this year," Hanson says. "Can you still go running around, chasing dangerous people, and doing dangerous things when you have an infant depending upon you for a whole life? That is grist for the mill for the two of them. One of the great things about having this child is that it makes everything very immediate and very gut-oriented. It's gut versus brain. What do we do?"

Bones premieres Thursday at 9/8c on Fox.