Credit: Greg Gayne/FOX Photo: Bones and Zack Go Over Some Remains in Season 5, Episode 16: "The Parts in the Sum of the Whole"
Of all the characters on Bones, Zack Addy has been the hardest for fans to understand. He's intelligent and socially awkward like Brennan, but he also seemed to enjoy the camaraderie of the lab (in his own way, of course). We were told he was too wimpy to be in the armed services, and yet he aided a serial killer? We need more of the enigma that is Zack Addy! Here are five reasons we miss our boy.

5. Zack helped Angela and Hodgins bond
Giving Zack advice helped Angela and Hodgins bond as a couple that much more quickly. Not to mention that having Zack ask earnestly about dating and "interacting with humans" made him that much more adorable. Plus, his awkwardness elevated Bones to "social butterfly" status by comparison. Zack's misguided but adorable crush on Brennan was sweet too. Really, it was hard not to root for Zack!

4. Zack is unfailingly faithful
Despite his lack of interpersonal skills, he understood the importance of solidarity and friendship and was extremely loyal to the team. More than once, he covered for Hodgins or took the blame for a slowdown in lab work. He also gave credit where it was due, which made him a stand-up guy. And the fact that he was a rules dude? That just made the rest of the team want to break those rules, which increased the fun factor for us!
Credit: David Livingston/Getty Images Photo: Eric Millegan at the Opening Night of White Christmas at the Pantages Theatre in Hollywood on November 28, 2005
3. Hodgins needs another guy friend
Zack was Hodgins's best guy friend in the lab. Yeah, Hodgins is close with Angela because she's his wife, but it isn't the same as having a bro to bond with. Not that Hodgins ever really bonded with Zack in the traditional sense, but what's traditional about studying slime, bones, and bugs all day, anyway? Zack was harmless enough that Hodgins didn't feel threatened by him. (We also miss Booth's special relationship with Zack, which involved ignoring him. Still, it was special.)

2. Zack never ceased to surprise us
Just when you had Zack figured out, he totally switched things up on you. Case in point: We weren't surprised to learn that he ate macaroni and cheese every single day for lunch (the routine gave him comfort), but we were surprised to discover that he was singer as a kid. And despite looking like a wimpy kid who couldn't fight his way out of a paper bag, he told Cam that he does 100 sit-ups and push-ups every day along with weight training. Zack as a badass? Intriguing.

1. Zack's departure was unsatisfying
There were too many questions left unanswered after Zack left the show. Just how did he get involved with The Master? Was he really "detrimental to a military team approach" when he went to Iraq? Or was that just a cover for him being a secret spy? How was he able to leave the mental institution any darn time he liked? We need more answers!