Some assumptions about Coulson's death were simple, that it was faked so that Nick Fury could motivate the Avengers using Coulson's treasured Captain America cards which -- as Agent Maria Hill noted -- from his locker, and not his body. Coulson simply went into hiding after that, the theories say.
However, the pilot hints at what really happened to Coulson (Clarke Gregg). It appears he was indeed resurrected after his death in "The Avengers." His fellow TV agents and S.H.I.E.L.D. colleagues will say that Coulson "must never know the truth” about his death.
Our theory is that Coulson is an LMD, a Life Model Decoy or android as in Marvel Comics. In order to possess Coulson's memories, his brain patterns would have been imprinted on the LMD's brain (simple for comics, right?).
Perhaps as part of a gimmick to keep you watching, the full story will be long in coming, though. That's something that we were already aware of, but as co-creator Jed Whedon said,
We can’t wait to pull the curtain back on that. [But] we’re going to take our time.This move is similar to how some shows will drag out a romance for years to keep viewers interested.
It's unclear why viewers would need such help. The stories, according to Whedon, will weave in and out of the storylines of Marvel movies. Whedon said:
We plan on trying to weave in between the films and try to make them more rewarding on both ends.
In any of these [episodes], you can always ask, "Why don't they just call Iron Man?" They are aware of each other, but they do have to have their own lives.Marvel's head of television, Jeph Loeb, also added:
When fans see this pilot, they'll be pretty astonished by what we pulled off and the challenge is to do it every week.You can expect stellar special effects, too -- at least for television. Gregg previously claimed that "Marvel's Agents of S.H.I.E.L.D." has "incredible visual effects and stunts" unlike anything "seen on TV before."
The magic of television is that it's about characters, and fortunately that's also what Marvel is also about. We're not built around a cape and a cowl.