Dark Reign (comics)/WMG

Osborn's secret ally is a Red Herring
He's all just a very powerful illusion created by Doom and Loki in order to manipulate Norman and rest of the Cabal.

Osborn's secret ally is Miracleman
Marvel bought laws to the character this year and the doesn't want to tell anybody if he will become a part of Marvel Universe or get his own, separate one. They are going to make his never created "Dark Age" arc which will end with him begin thrown out from his would and transported to Earth 616, where he will lost his memory and become Osborn's puppet.
 * ... under the name "The Sentry".

Osborn's secret ally is Heart of Earth
He found whoever is the heart of Earth and brainwashed into becoming his servant.

Osborn's secret ally is Dr. Manhattan
That explains why Taskmaster screamed "What the hell is that?" when he saw him - naked blue man just asks for that question.

Norman caused One More Day
He make a deal with Mephisto which required forcing Peter to do something terrible - sacrifice his marriage and make a Deal with the Devil - and forget it, which at some point will be revealed to him and cause one serious Heroic BSOD and giving Osborn great political power and connections. This may lead to conclusion that Mephisto is Osborn's ally.
 * This would also explain where he got the dumb as dirt idea to conquer Asgard, where, depending on the writer and sources, the kids are as strong as Spidey.

One More Day caused Dark Reign
Spider-Man makes a deal with Mephisto and soon after his Arch Nemesis takes over? It can't be a coincidence.

Zodiac is Arrancar created from Light Yagami's and Heat Leager's Hollows
Wich explains why he looks like former and acts like Joker played by latter. Zodiac Key become his zanpankuto which he needed to take back in order to get his Arrancar powers back.

Osborn's ally is brainwashed Haruhi
C'mon, if you wants to keep god, man connected with powerful demon and Dr. Doom in line, you need somebody like her.

Sentry was created by Beyonder
He has the same abilities as Molecule Man and we know there's a connection between Owen and Beyonder, and they don't like each other. Right now Sentry defeated Molecule Man. Beyonder created Bob as a part of his Xanatos Gambit to mess with Owen.

Taskmaster will be the one ultimately responsible for bringing down Osborn.
It's pretty clear that Tasky doesn't want anything to do with the Cabal anymore, and is only going to stick around so long as his life is being threatened. He's going to be looking for an out. An interview I read said he's going to be important to Siege. At least two sources have him saying out loud he knows the current situation is going to end up in disaster. Connecting the pieces, I see Taskmaster betraying Osborn when the time is right, which the Rule of Drama will dictate as being just when everything looks like the guy is going to come out on top and conquer Asgard. It offers him an out from both the Cabal and the fallout of Dark Reign that most villains are going to feeling when they aren't on top of the world anymore. All pieces considered, there's no reason a guy like Taskmaster WOULDN'T snatch up an opportunity like that.

Sentry is Brian Bendis
TO quote an idea from CBR forum:

"Since New Avengers #1, Bendis has doled out clues about the absurdly powerful, yet oddly ineffectual super-being called the Sentry, a hero whose every good work is counterbalanced by the villainy of his arch-nemesis (and alter-ego), the Void. In this latest issue of Dark Avengers, Robert's wife Lindy relates her own theory about the Sentry. She posits that Robert's abuse of "the serum" opened him to energy of "Biblical proportions", and her theory receives partial corroboration with a flashback to Old Testament times, showing the avenging angel of the Tenth Plague to be the Void-energy itself, possibly channeled by a Hebrew prophet. Lindy says that it's just her Sunday School perspective, but she's sure Robert became "a part of something larger and crazier than anyone has even considered." Even if Bendis made the ballsy move of introducing Yahweh into the pantheon of Marvel gods, the Void who taunts Lindy is no angel. He's sardonic, cruel and unabashedly evil—and he finds Lindy's theories hilarious. He even quips that he is Galactus.

When writer Paul Jenkins introduced the Sentry, the standalone limited series could be read as a story within a story. Robert Reynolds could be seen as a character in the real world—our world—who escaped his psychological handicaps by imagining himself into a fantasy world: the Marvel Universe. There, he dreamed himself a hero, and inserted himself into Silver Age continuity as fast friends with the superheroes, he himself being the mightiest among them. He even married his all-American girl sweetheart with a similarly alliterative name. His nemesis, the Void, represented the nihilistic truth that Reynolds was really a powerless nobody. The limited series could be interpreted as a tale of the healing power of fantasy.

When Brian Michael Bendis brought the Sentry into Marvel continuity, he preserved the trope that Jenkins' Robert Reynolds imagined: that the Sentry was one of the original heroes, and the world had forgotten about him. There was, of course, a comic book device to explain the gap in memory (the Sentry's psionic powers), but in the first Sentry arc, writer Paul Jenkins appeared—as a character—in the pages of New Avengers, dumbfounded at how his fictional creation was standing before him in real life. Flashbacks to the Sentry's past, originally shown in campy Silver Age art and writing style, began to morph into a decidedly modern comic book style. A flashback about the Sentry's first encounter with the Skrulls mutated from a "Mars Attacks!"-style scene to a grim analogy to the 9/11 suicide plane attacks by religious fundamentalists. Marvel history was being re-written, almost as if a comic book writer was re-casting old stories to modern sensibilities. Or a childish fantasy was being upgraded in sophistication and made manifest. Perhaps the most concise description of the Sentry's nature was in this week's Mighty Avengers #33, when Stature describes the Sentry's clash with the Void as "a damaged psyche playing out the conflict of its dual nature through comic book archetypes."

Robert Reynolds' godlike powers aren't those of Yahweh; they're those of a writer with respect to a comic book universe. Robert Reynolds is a man who can retcon himself into comic book history and make himself a peer of the Earth's Mightiest Heroes. But he then becomes beholden to the rules of the comic book universe and its narrative flow, and keeps himself from over-influencing the course of the story by checking himself with special weaknesses and an arch-nemesis who can counter his every move. In Dark Avengers #13, the Void taunts Robert: "You should just take a step back and look at what you've accomplished as the sentry. Nothing. You want to do something? Allow me." Because that too is one of the rules of comic book stories: the heroes are reactive defenders of the status quo. It's the villains who drive the story forward by acting. By acting badly.

Bendis, in Avengers: The Illuminati #3, established the godlike Beyonder as a being interested in wiping his own memory and inserting himself into the lives of the superheroes. Doubtless, there will be a revelation that Robert Reynolds, the Sentry, the Void, Cloc, and even Lindy are all constructs of the Beyonder, playing his game. But I like to think that there is a hidden truth behind that revelation, one that Marvel will never show. Robert Reynolds' true power is that of authorship of Avengers continuity. And his true identity? Brian Michael Bendis."

The Void was an advanced scout for the Friends On The Other Side.
As per the Disney Animated Canon WMG page the friends have been scouting out the Marvel Universe since it was bought by Disney. He granted Norman his power both as the Sentry and the ability to fool the world into thinking he was anything other than pure crazy evil. When Norman's debt came due and he was unable to properly pay it lead him into the unwinnable scenario of the Siege where he was thoroughly defeated. In order to cover it's own tracks the Friend!Void faked it's own death when it was crushed by the Hellicarrier and returned to the other friends in secret.

Loki helped defeat Osborn to repay Spider-Man
Loki spent most of Dark Reign screwing with Osborn's mind and driving him slowly toward insanity as a way to repay Spider-Man for the time they teamed up in Amazing Spider-Man #503-504. Loki promised Spidey he'd repay him some day. Taking down his worst enemy is a pretty good way to repay him.