Someone from Brennan's (Emily Deschanel) past will return in the final season of "Bones."

TVLine revealed that Brennan's missing ex, Tim "Sully" Sullivan, will make his long-awaited return in the 12^th season of the long-running crime drama.

Fans of the show could remember that Sully and Brennan began seeing each other in season 2, after the FBI special agent asked her out on a date. Their relationship seemed to be smooth-sailing, until Sully decided to go on a year-long Caribbean trip aboard his new boat named Temperance. He asked Brennan to join him on his trip, but she opted not to go. Before he left, he promised her that he would return after a year, but it never happened.

Actor Eddie McClintock confirmed via Twitter that his character Sully will return after a decade in the farewell season of "Bones." But it is still unrevealed how Sully's return will affect Brennan and her husband Booth (David Boreanaz).

Aside from Sully, Brennan and Booth's relationship will also be threatened with the return of her former protégé Zack Addy (Eric Millegan).

In an interview with TVLine, co-showrunner Jonathan Collier revealed that Zack's return will bring no danger to the couple's lives, but it will have a major effect on their marriage.

"The Zack [storyline] is certainly going to place them in jeopardy and certainly place them with different viewpoints," Collier said. "But is it going to challenge their marriage? I think their marriage is stronger than that."

The co-showrunner also revealed that there will be a lot of threads that will be tied up this season.

"There's also Booth's spiritual debt... a debt of killing that he wanted to pay off," he stated.

At the moment, FOX has yet to reveal the official release date of the premiere episode of "Bones" season 12. But the series is expected to air sometime in 2017.