'Arrow' Season 4 SPOILERS: Showrunner Previews Oliver, Diggle's Damaged Relationship

Oliver Queen and John Diggle had some major issues toward the end of Season 3 of Arrow, and executive producer and showrunner Wendy Mericle has now shed some light on their damaged relationship as Season 4 begins. [SPOILERS to Follow]

Oliver went undercover as the Heir to the Demon in the final episodes of Season 3, and part of that mission involved kidnapping Diggle's wife, Lyla. From that moment on, the trust broke between the two friends, even after Oliver revealed his plan.

So when Season 4 begins, there is still plenty of bad blood between the two.

"Dig has a huge bone to pick with Oliver when they see each other again at the top of Season 4," Mericle told Collider. "We’re gonna work that out. It’s not gonna be easy. With what happened to Dig’s family, it’s really tough to buy that back, and Oliver is not gonna to be able to. Obviously, they can’t be mad at each other forever, or what are we doing? But also, in the intervening months while Oliver has been gone, Dig has, more or less, been leading the team. It’s a little bit more democratic, Speedy and Black Canary are both super bad-ass and kicking butt. He’s not happy, when he and Oliver meet again. It’s not an open-armed, 'Hey, buddy, all is forgiven,' reunion."

We've also heard that Diggle will finally be getting a mask this season in order to protect his identity as he leads Team Arrow in Oliver's stead. This is a development that fans have been waiting for since the beginning, as Diggle has been running around with no mask helping out all these costumed heroes on missions. But will he have the code name Guardian as some fans have predicted?

"By necessity, he can’t be Diggle out in the field," Mericle said. "I can’t tell you what the code name is, but he’s gonna have a fun, cool code name. He’ll start to embrace a little bit more of that dual identity conundrum that Oliver has been grappling with for three years now."

Season 4 of Arrow premieres on Wednesday, October 7th at 8 p.m. Eastern.

How do you think Oliver and Diggle will heal their broken relationship? Let us know your thoughts in the comments section below.