The current storyline on "Agents of S.H.I.E.L.D." explores the "What if?" moments of certain character's lives. For Phil Coulson it's, "What if I didn't join S.H.I.E.L.D.?" For Melinda May it's, "What if I didn't kill the Inhuman child in Bahrain?" As each character lives out their regret-free lives within the Framework, Daisy Johnson has the difficult task of trying to wake everyone up. Throughout the last five episodes, each character will have to learn the value of regret and how one simple choice of theirs that they regret, could actually be what saves the world from Hydra.

During interviews with small groups of press including CBR earlier this month at WonderCon in Anaheim, Clark Gregg, Chloe Bennet and Marvel Television President Jeph Loeb discussed these "What if?" moments. During the roundtables, Gregg began to tell the story of how Jon Favreau invited him to be a part of the first "Iron Man" movie. Gregg accepted the part, despite knowing that it was a small role that he may have been cut from. As Gregg began to share, Loeb pointed out that if Gregg had not joined the Marvel Cinematic Universe, that seemingly small decision could have had major consequences, just like if Coulson had never joined S.H.I.E.L.D. It was a profound moment of realization that has some interesting parallels to both the series and the real world.

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In the April 4 episode of "Agents of S.H.I.E.L.D.," which is aptly titled "What If...," Coulson teaches history at Alexander Pierce High School. He is not the Coulson that viewers know from the MCU. This Coulson is afraid of Inhumans and is loyal to Hydra. He doesn't collect Captain America trading cards or work for Nick Fury, and yet there are similarities between him and the man whom we as Agent Phil Coulson.

"He loves history, he studies the history of S.H.I.E.L.D.," Gregg said. "He says, I think in [episode] 14 or 15, 'All the grief, everything, all the loss, everything that I’ve done, that I’m ashamed of, all of that came from after I joined S.H.I.E.L.D.,' so it’s removing that regret that has him there as a history teacher. To have played this guy for that many years... being dropped into this alternate world where Hydra’s in charge, as a completely different innocent kind of person, has been such a thrill and such a breath of fresh air. Who is this person essentially and does [he] start to emerge again in a different way? That’s really thrilling."

While Coulson may be the same man underneath the Framework, Loeb pointed out that not all heroes have to be S.H.I.E.L.D. agents, and that just because Coulson is a teacher, that doesn't negate his status as a hero. "One of the things that is so exciting for me," Loeb said, "Is the moment when you tell Simmons -- who you don’t know in this world -- that you’re just this history teacher, and the fact that she argues with you and says, 'Yes, you’re right, you are a leader, you have an impact,' not only speaks to you as your character is, but I think also -- and this is what the show does so well -- is that it always comments on the fact that there are heroes around us, in this world, and whether or not they are policemen, or nurses, or teachers, they are constantly around us, they are kind of our own versions of Agents of S.H.I.E.L.D., that really make a difference in this life."

While Coulson has been an agent and a director on "Agents of S.H.I.E.L.D." since 2012, his journey actually began earlier than that. "I think it was in 2007 when I was shooting 'Iron Man 1,' and they kind of kept adding scenes for me. Here was a guy who was kind of undercover as a goofy bureaucrat, and who had a lot more power in S.H.I.E.L.D. then he let on," Gregg told reporters. "It’s been a long evolution and then within the show, you know, it went from being what, maybe an hour in all the movies together, to 22 hours the first season of 'Who is Phil Coulson and this team around him?'"

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"I always love when you tell this story," Loeb said. "Jon Favreau called you and said, 'Hey will you come and do this little part in "Iron Man,"' and you sort of though, 'OK, I’ll..." Gregg then added, "I saw that cast and thought I was going to get cut out… I’m going to tell everyone I’m in this because I love the comics and then it’s going to be, 'Who do we cut, Jeff Bridges, Gwyneth [Paltrow] or Clark?' Nine years later, here I am. It’s a really good point -- the tiny choices you make."

Gregg could have been intimidated by that cast and sought a different role, but he didn't. As Loeb said, "So if you had said, 'I’m going to do this instead...'" we wouldn't have Coulson today.

Loeb then turned to Bennet and pointed out a real-world choice that she made that could have kept her out of the MCU. "But then again, the first time that you [Chloe] came to see us," Loeb related, "You got pulled over by the cops and got a speeding ticket. There is a world where you could have, at that point said, 'I gotta go home, I’m so upset, I can’t go to that meeting.'"

Bennet retorted with an emphatic "Hell no," stating that she got the speeding ticket because she was racing to the audition. But Loeb's point was clear: Both Gregg and Bennet have become iconic characters in the MCU, and without them, Marvel's live-action world would look vastly different today. "Agents of S.H.I.E.L.D." would not exist without Phil Coulson, and if Gregg had turned down Favreau during the first "Iron Man" almost 10 years ago, we may not have a show at all.

Thankfully, that's an alternate universe fans will never have to experience.

Airing Tuesdays at 10 pm ET/PT on ABC, “Marvel’s Agents of S.H.I.E.L.D” stars Clark Gregg as Agent Phil Coulson, Chloe Bennet as Daisy “Quake” Johnson, Ming-Na Wen as Melinda May, Iain De Caestecker as Leo Fitz, Elizabeth Henstridge as Jemma Simmons, Henry Simmons as Alphonso “Mack” Mackenzie and more.