The Real Reason Zack Addy Left Bones

Of all the characters that have passed through the Jeffersonian, none carved a bigger place in the hearts of Bones fans than forensic anthropologist Zack Addy (Eric Millegan). The (usually) shaggy-haired, socially awkward, multi-talented genius spent three seasons winning us over with his well-meaning ways (even if they often missed the target) and brilliant analyses (which rarely did). That's why the decision to cast him as — very old spoiler alert — the apprentice to a cannibalistic serial killer and send him to a mental institution at the end of the third season was met with raised eyebrows and more than a little fan outrage.

Millegan returned for a few guest appearances and flashback sequences, but after season five, he disappeared from the show seemingly for good. It would be six years before we saw Addy again, and during that time, Bones fans took to forums to wonder what in heck had happened to him. After returning for a dramatic season 11 finale, Addy finally got his semi-happy ending in the show's final episodes.

But why did Millegan step away from the show in the first place? Here's the real reason why the actor left Bones.

Often, characters are written off of shows at the actor's request: crime drama fans may know that's the real reason Sasha Alexander left NCIS after season 2. But that wasn't true in Millegan's case.

During the filming of season three, Millegan was summoned to a meeting with Bones creator and producer Hart Hanson and writer and producer Stephen Nathan. At the time, no one knew the identity of the Gormogon — the serial killer with a taste for human flesh — and his apprentice. In the meeting, the pair revealed to Millegan that Addy had been pulled in by the Gormogon's ideas and was the one assisting him with the murders. (That turned out to only be partially true.) "It wasn't my choice," Millegan explained to TV Guide at the time. "It was a creative decision to shake things up and make a good season finale."

Millegan said that after clarifying that Addy was not a cannibal, he had mixed feelings about the revelation. "I tried not to focus on the fact that I was going to be off the show, and focus more on wow, look at all this great material they are giving me as an actor," he said in an interview with PR firm Andrew E. Freedman. We suppose that if you have to go out, you should go out with a bang... and, er, a possible link to a cannibal.

If you're enough of a fan to be familiar with the untold truth of Bones, you're already aware that the show has had its share of behind-the-scenes drama. But despite what the rumor mill will tell you, Millegan never linked his departure to his bipolar disorder. Quite the opposite: he has repeatedly said that the show's team was always supportive of his mental health, especially creator Hanson and co-star Emily Deschanel.

Millegan shared his bipolar diagnosis in a two-part Huffington Post piece in 2011. He explained that he had a tough time dealing with depression and mania while shooting the first season of Bones, partly triggered by moving from New York to LA for the series. He was diagnosed in 2006, during the first season, and eventually found a combination of medications and therapy that helped stabilize his condition. "Bipolar disorder is a scary disease, but it is manageable... take your medicine, get to people who are supportive of you, and know that you can get through it," the actor said in his chat with HuffPo.

He also expressed gratitude that had Bones helped him to get through some of his worst days, saying, "I feel I probably would have ended up in a mental hospital if it weren't for the structure that Bones gave me." Hanson, in particular, took it upon himself to watch out for the young actor; not only did the Bones creator promise to hold Millegan's job for him if he needed medical leave, he researched bipolar disorder extensively. If you've been keeping an eye on what the cast of Bones is doing today, you'll know that Millegan is still advocating for mental health — and taking time to find the right opportunity to return to television.