The Bones season 11 finale featured the return of a very familiar face, but why did the show's producers decide to bring him back?

***Spoilers through the season 11 finale of Bones ahead***

The finale of Bones season 11 featured Brennan (Emily Deschanel) and the rest of the Jeffersonian team looking into the Puppeteer case, only to discover that much of the evidence suggested it was Zack Addy (Eric Millegan). Fans will recall that Zack was a Jeffersonian intern from the first few seasons who was ultimately locked away in a mental institution after aiding a different serial killer.

Then, Zack appeared in the final minutes of the episode and kidnapped Brennan, leaving Bones fans with one heck of a cliffhanger.

Bones executive producer Jonathan Collier spoke about this shocking twist and what went into having this all come together in the finale.

"It really came down to knowing that these are the last 12 episodes we're doing this year," he explained in a new Entertainment Weekly interview. "We thought: 'This whole next season is about wrapping up loose ends, finishing business that was started - relationships, characters, we want to tie up as much as possible.' And we really want to make this a season that is exciting and meaningful, that pays off for our characters and rewards the fans that have put so much into the show. Once you come to that, who's better to bring back than Zack?

"Because that was really unfinished business, and we've always been very, very fond of the character that [series creator] Hart [Hanson] created," he continued. "I came to this show at the beginning of season 7, so for me it's really gratifying to be able to make moves like this. And with Hart's blessing. He's been both helpful and supportive of everything we've been doing."

Collier also teased that Zack's return is the first of many surprises heading into season 12.

"We're doing a lot with our characters. We're revisiting some stories that began very early in the series," Collier said. "It's only 12 episodes, which is a blessing and a curse. It's a curse because it's fewer episodes. It's a blessing because you can really make them tight and move them through an arc."

The final season of Bones begins in 2017 on Fox.

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