When Sentry was first created, the “void” appeared to be a psychological construct reflecting Bob Reynolds’ personal limitations and insecurities.  Over the course of Brian Michael Bendis’ work with Sentry, the Void has become something that lives outside of Reynolds–and these issues make it very clear that Void is an entity all its own.

This arc starts in 1600 BC, with the Void being part of the first Passover(!).  Immediately following that opening scene, Osborn gives Sentry a “cure” and Sentry’s entire origin gets retconned to where he was a junkie searching for drugs who accidentally drank the Void.

This is all much less interesting than the original vision of the character.

Lindy, Bob’s wife, “kills” him–but all that really happens is that Void takes over Bob’s body.

Bob essentially goes crazy, and this paralleled with Norman Osborn finally succumbing to his own craze, dark (dark green), evil(er) side.  In order to fully free the Void, Norman has Bullseye to kill Lindy, Bob’s wife.  Bullseye does it, and makes it look like a suicide–to manipulate Reynolds further towards insanity.

This makes Sentry go full Void.

Osborn and Void apparently speak the same language because Void is now Osborn’s full partner.  At a meeting of the Cabal, Osborn orders the Void to kill the insubordinate Doctor Doom…

Void blasts Doom (but, of course, it’s a Doombot), and Osborn tells the President that Doom committed an act of war and had to be killed–and now the United States must go to war with Latveria.

This, creating a war on false pretenses, is the straw that finally breaks Victoria Hand’s back–and leads directly into Siege #4.