A Study in Crimson and Viridian

Rating: PG (ratings vary per chapter)
Characters/Pairings: FrostIron (Loki/Tony), canongirl!Tony Stark(i.e. Natasha Stark), and the rest of the Avengers movie cast.
Warnings: Movie spoilers, obviously, and in a major way. Spoilers for various events throughout the comic-verse, including Civil War, Dark Reign, and Siege.
Disclaimer: None of this is mine. Well, except Earth-199990, but that's pretty useless to me without all these great Marvel characters.
Notes: Takes place before and leads up to the Avengers Movie-verse, with some mentions of Earth-616 and Earth-3490. Largely based off the movie (major, major spoilers in this regard!), but ultimately it will branch off into something new. I'm actually not a big het fan, but this idea intrigued me. If Natasha Stark marrying Steve Rogers could prevent Civil War, what would happen if Natasha Stark met Loki?

PROLOGUE

Three months before the Chitauri invasion, in another universe, Reed Richards develops a two-point singularity power source. It is his hope that with this new creation, the uncertainty engine he's been working on can finally be put to the test. Essentially, the engine would work as an observational device, allowing him to peer past the veil of the universe into other, similar, realities.

He calls it The Bridge.

In the aftermath of the civil war between the superheroes, with Norman Osborn taking control, Reed commits himself to finding a solution. To better analyze the situation, he would need to dissect the events of the previous year, comparing the data of the events of this universe to that of other realities.

The universe is timeless and the realities are endless. Of the infinity-and-one possibilities, he manages to narrow his search to about 418 realities in which the legislated superhero registration act did not result in a conflict within the metahuman community. He sweeps through those, studying the histories of variant Earths. Years are condensed to minutes or seconds—he does not know—and he observes with all the objectivity of a scientist the possibility of Tony Stark's involvement as being a common factor in prolonged conflict.

Not all the realities mirror his Earth in likeness, but he is more interested in the events than the architecture. He takes note of particular case studies in which conflict is averted altogether when Tony Stark and Steve Rogers (or Natasha, in some instances, and Stephanie in others) are romantically involved.

Other times, Reed's stomach churns with the situations The Bridge presents him with. They are barbaric and cruel at their worst, and at their best, serve only to amplify his guilt for his involvement in the war.

He is lost in his thoughts, only half paying attention to the stream of footage, when the reality shifts into the next one. At first, it appears to be another instance where a female Tony Stark becomes involved with Rogers, and Reed is making another note regarding Stark's detrimental influence when—

Oh?

He pauses the timeline, almost a second too late as the world seems to already be dissolving along the fringes into the next reality. For a moment, he can only blink as his brilliant mind tries to register what he has seen. What he thought he saw …

The action in itself is pointless, for the images are being projected directly into his mind. Nevertheless, it dispels the transitory shock in favor of familiar curiosity and he instructs the computer with his mind to feed him all relevant information pertaining to the reality he is being shown.

Earth-199990, he is informed, a reality that features much of the same as his Earth, though there seems to be some differentiations in historical events and a pointedly evident lack of super hero activity. Xavier and his mutants struggle, as always, to fit into this world, but as far as superhumans go, this universe produces them sluggishly. He finds 'himself' and the other Four, but they lead markedly simpler lives with only the occasional resurgence of Doom. Every now and then, Magneto appears to disrupt the peace, but this reality's Magneto has only recently declared his war against the 'primitives' and Xavier's kids do a fair job handling him and his followers.

He shifts his focus to the few other heroes, sifting through their timelines within this Earth and searching…

Nothing.

No war.

There is an incident, which leads to a call for all self-proclaimed 'heroes' to register with the government. It is resolved without conflict and without the identities of any hero being unwillingly compromised. The SRA is rejected, and later, the MRA is retracted. There is peace and acceptance—or as close as the Earth can get to a semblance of it. There are still those who would challenge it, but the heroes of this reality seem to have one unlikely advantage.

Loki.

It is difficult for Reed to focus his thoughts and The Bridge responds by projecting dozens of images in answer to each question that pops up in his head. Of the infinity-and-one realities, of the 418 worlds in which the Civil War between superhumans had been resolved peacefully or avoided altogether, Earth-199990 depicts a reality where, while far from perfect, is relatively—enviously —more stable than Reed's Earth or any other he's seen.

Clearing his mind as best he can, he focuses on the God of Mischief. Loki's timeline is then stretched out before his mind's eye, overlaid above the images of the other reality. It is a glowing green line running erratically throughout the over-arching timeline of the reality and Reed traces it as far back as he can, until he comes to the God's first interference with Earth. From there, he moves forward along the timeline, this time trading his attention between Loki's timeline and what is going on in the world.

Immediately, he cannot discern how Loki could have possibly influenced this reality positively. He follows the timeline to a point he estimates would roughly coincide with Reed's reality, but though the issue of registration arises, it is nothing as drastic as what Reed and this Earth experienced.

Reed hesitates.

Then, telling himself he will not look into his own timeline or that of the Fantastic Four, he pushes forward along Loki's timeline. In any event, this is not my future, he reasons with himself. It is already so different from his own reality that he doubts the future of the reality in Earth-199990 would reflect his Earth.

Reed skims Loki's future, forcibly restraining himself from indulging in curiosity more than he already has. As a result, many events make little sense to him, and at one point he is tempted to retrace his steps across the timeline when he sees the mythic city of Asgard hovering over the rural plains of Oklahoma. Eventually, he relents that there is nothing to learn of the future and his pursuit has only heightened his accursed curiosity.

Going back to the 'present', Reed pauses the timeline again to think.

This reality is so very much what he desires for his own, but he cannot determine the key events which allowed for it to happen.

He permits the timeline to play out again from Loki's origin on Earth, this time taking care to examine every detail.

The timeline begins with only a faint intimation of the God in the form of the Destroyer, which is eventually defeated by Thor. There is a year of absence, and then Loki appears once more, in pursuit of the Cosmic Cube. Reed cannot see into the timeline beyond Loki's actions on Earth, but he expects the God must be allied with another. This Loki is powerful, but in a strange way, he appears young and almost uncertain of himself. It is not a Loki he is familiar with and Reed studies him with interest.

And then—

Yes. There it is.

What first drew his attention to the timeline when the images had been flickering through his mind, before he'd become distracted by the events of Earth-199990. He'd thought it a trick of his mind, perhaps. But no. There it was again.

Reed slows the pace of the timeline so that minutes are days rather than years. He needs to understand.

This is what he sees.