This story contains minor spoilers for the Fox series, "Bones."

Fox's medico-crime series, "Bones," has a habit of dividing the fanbase that have sustained the series for the last five years.

Among the biggest splits was the decision to turn Zack Addy (Eric Millegan), the bright and energetic protégé of Temperance Brennan (Emily Dechanel), into the follower of a deranged cannibal. Then, only a year later, the fans erupted again in what can only be called a hit-and-miss season finale.

And now it looks like it's going to happen all over again with the shows 100 th episode, featuring the return of Zack and a trip down memory lane.

"Oh, I would guess that the episode is absolutely going to split fans," Marisa Roffman of Zap2It said. "There will be those that don't like what goes down while others will respect and appreciate what the writers have done. I predict that people will feel as passionately about the 100th as they did about the fourth season finale... though that is not to say that the same people who hated the finale will hate this episode (and vice versa)."

The episode, entitled "The Parts in the Sum of the Whole," is set to air on April 8 and will return to the classic "Bones" days when Zack was still a lab assistant at the fictional Jeffersonian Institute and will also include the first every partnership between Brennan and FBI Agent Seeley Booth (David Boreanaz). The outing will also feature the first encounter between Zack and Booth, a key event in the interpersonal skills of both characters.

However you feel about the episode though, it will apparently be a good step for the popular will-they, won't-they relationship of the core duo.

I would say it's a good step for the show," Roffman said. "For Booth and Brennan fans, it's quite a ride. There are things that might feel like a pencil has pierced through your heart. But there are also things you've waited years to see."

"Bones" airs Thursdays at 9 p.m. ET on Fox.