"For me, one of the really cool things about this is that throughout these movies, there have been - and I enjoyed it this way - hints at what S.H.I.E.L.D. is and how they function within this Marvel movie universe which, as you know, is deeply based in the comic books."

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But what I've also really liked about it is that it not only has Marvel set about... if they just were slavishly trying to bring the comic books to life, literally, I don't the movies would work, because it's different to see something on screen in three dimensions with actors, and they kind of, I believe, are constantly trying to find a way to absolutely respect the source material and at the same time, transform it into something that works and that you believe on screen.

— Clark Gregg