So the latest event/multi-comic crossover from Marvel is called Original Sins written by Jason Aaron. This event involves the death (surprise!) of the Watcher.
The premise of a mystery that reveals a tenebrous side of the Marvel universe reminded me of another mini-series written by Dan Abnett and draqwn by Igor Kordey in 1998 called Conspiracy:
In this series, a reporter stumbles across a cold war conspiracy among several key figures in the Marvel Universe (Howard Stark, Bolivar Trask, General Haywerth, Thunderbolt Ross, Edward Harrison) to arrange circumstances that will end in the creation of American superheroes.
Inspired by a blend of X-files and Marvels, the series rewarded fans by connecting the dots between several significant Silver Age Marvel events in a way that felt respectful to the source material. A fantastic review of the series can be found at The Comics Cube.
I think the key with a series like this is that you suggest connections to the readers but still allow wiggle room for there to be other answers. That way you don't devalue their (precious!) knowledge of continuity.
And I think that's where Original Sins is going to fail. While I doubt there will be anything that subverts continuity in the way that Conspiracy did, be on the lookout for grand scale icon tarnishing. And while it might seem a bit fannish for me to say that's a flaw, here's the problem. If you show a character who has been always portrayed as making the heroic decision for decades making a real line crossing call early in their career, how is that supposed to work exactly? Were there no ramifications in the character's personality or attitude after said dark decision? You've sort of just underlined the unreal-ism of the entire genre by doing that haven't you?
It would be like having a Conan story where the barbarian meets a young son who is the result of celebratory night with some wild wench and then showing Conan all torn up about the act of bringing a boy into the world without a father to guide him.
How do you then turn around and tell business as usual Conan stories after that?
I'll be interested to see how Original Sins turns out.