Christopher Markus and Stephen McFeely were present at the TCA Winter Tour yesterday to promote their ABC series Marvel's Agent Carter, but the writers also shed new light on their highly-anticipated superhero sequel Captain America: Civil War, which kicks off Marvel Phase Three next year. The writers teased that the Civil War story line, which pits Avengers Tony Stark (Robert Downey Jr.) and Captain America (Chris Evans) against each other, has been in the works for quite some time. Here's what Stephen McFeely had to say in an interview with IGN.

"It's been on and off the table for a while, let's put it that way. And it's a challenge to do it and make sure that all the characters that we've established, and everyone's established in the MCU are serviced and sound correct, right? Because there's a difference between the characters in Civil War, which was written in 2006, 2007. The MCU doesn't exist [when it was written]. There isn't a Robert Downey Jr. or Chris Evans who has helped create the character so we need to make sure that that template gets adjusted and what have you in order to make sure it services these characters and not just sort of rip off their parts and make them look like them."

The writers' Marvel's Agent Carter series establishes Peggy Carter (Hayley Atwell) and her working relationship with Tony Stark's (Robert Downey Jr.) father, Howard Stark (Dominic Cooper). When asked how Peggy may be featured in Captain America: Civil War, Stephen McFeely had this to say.

"As we have not started shooting, and I'm on my fourth draft of many, that question [of who Peggy was to Tony Stark] has been in and out all over the place so who knows. So many things can shake out but we've had conversations and we pitched scenes. Some stay and some don't. But we saw [Peggy] in Winter Soldier, so we know she's around."

The writer was even more vague when asked how Chadwick Boseman's Black Panther will be introduced in Captain America: Civil War.

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"I'll keep that one close to the vest, but I'm very gratified that they went with Chadwick and that he said yes because he's a good get."

What do you think about these new Captain America: Civil War details? Do you think we'll see Peggy Carter in this Phase Three Adventure? How will Black Panther fit into the story? Chime in with your thoughts below, and stay tuned for more details.