How will Zack Addy's (Eric Millegan) return affect Brennan (Emily Deschanel) and Booth (David Boreanaz) in the final season of Fox's Bones?

Zack's unexpected return in the season 11 finale of Bones certainly put some interesting stakes into the upcoming final season. Zack kidnapping Brennan will certainly affect the Jeffersonian team in a major way, but will that extend to affecting Brennan and Booth's relationship?

"The Zack [storyline] is certainly going to place them in jeopardy and certainly place them with different viewpoints," Bones co-showrunner Jonathan Collier told TVLine recently. "but is it going to challenge their marriage? I think their marriage is stronger than that."

As for other storylines covered in the final season of Bones, Collier did reveal that there are "many, many threads we want to tie up" from earlier seasons.

An example would be the alarm clock mystery, a.k.a. what's up with all the 447 everywhere. Of this mystery, Collier said, "That has not been addressed," adding, "There's also Booth's spiritual debt... a debt of killing that he wanted to pay off."

Collier previously said at Comic-Con that they feel good about ending the series with 12 episodes.

"It's powerful and emotional, I've got to say, because the show has been so good to us; we've loved the show," he noted. "And there's something very bittersweet about ending it. I think we're doing it at a good time, at a good place, there's no question. I love the way we're doing it, I love having 12 episodes to do it in, all of that's right. But it's a big part of me now. I'm really going to miss it."

Bones season 12 will premiere in 2017 on Fox, though a specific premiere date has not been announced.