Zack (Eric Millegan) may not be who the others are expecting him to be in the upcoming season of "Bones."

Last installment, Brennan (Emily Deschanel) was kidnapped and her abductor turned out to be her former intern. Zack was a brilliant protégée and on his way to a great career until it was revealed that he has mental problems. When a case the Jeffersonian was working on turned out to be connected to him, his life was ruined. Zack was supposed to be locked up in a psychological facility, but he somehow managed to escape and got to Brennan.

While speculations claim that Zack is the serial killer "The Puppeteer," recent rumors reveal that he is not. As per HNGN, he is actually the criminal's sidekick. Later on though, Zack will change his mind and help Brennan escape. As a consequence, he will die instead of her. It is difficult to discern what was really going through Zack's head when he abducted Brennan. If he does end up sacrificing his life for her, Booth (David Boreanaz) has to thank him for the rest of his life.

Brennan's predicament has been previously teased by showrunner Jonathan Collier. In his interview with TV Line, he shared that season 12 would be a tough time for her. It has been revealed that Brennan has been seeing a psychiatrist for quite some time now. She did not tell Booth that she was having a recurring dream about Zack. Her husband only found out about it during the finale, and by that time, it was too late. Zack already had her and Booth had no clue on where she could be.

"Nothing is off the table, because some very, very, very serious, meaningful, hard-hitting things are going to happen to Brennan," the EP teased.

"Bones" season 12 is expected to air midseason, sometime in early 2017.