AN: Hello again lovelies. Wasn't planning on writing again any time soon, but had this plot bunny niggling at me the last couple of days, and this happened. It won't be particularly long, just four chapters or so, but it's impossible to say how soon I'll actually be able to write them.

Contrary to what the title suggests, this isn't a crossover piece or at all related to my fic "Encounter"; however, it does borrow heavily from the concepts of equivalent exchange present in series like Fullmetal Alchemist and XxxHolic.

Disclaimer: I don't own the Avengers.

Chapter One: Arrivals

If people thought things would return to normal after the Battle for Manhattan, they were wrong. There was no "normal" to return to. Or perhaps, in those three days that had changed the world so dramatically, "normal" had simply changed with it.

Either way, there was no going back and humanity responded as always did: complain and argue, attempt to place blame, and eventually pick up its feet and trudge forward. And even the Avengers, none of whom had any sense of "normal" to begin with, were no exception.

Four years passed. The team gathered and met on random sprees of world saving, although never all in one spot again. Although not normal, life again fell into a sort-of pattern.

That was until the day that SHIELD detected an alien presence on the outskirts of the solar system—stationary, for the time being, hanging ominously in the outer belt amidst the asteroids. The entire world went on red alert (SHIELD could only be as discrete as their enemies would allow, after all, and if NASA could find the ship then heaven knew everybody else could), but when nothing changed after a week, a few optimists started to hypothesize that it might be a good development.

Any hopes, however, we shattered when the still newly-made Bifrost opened, returning Thor to Earth for the first time in nearly a year. With him came the news that theirs was not the only world that had picked up and rebuilt after the Battle of Manhattan.

War had arrived. But this was not the unprepared, seemingly benign planet that the Chitauri had seen fit to attack, so that when the call came they were prepared.

What they weren't prepared for, though, was that when the Bifrost opened, it deposited not one, but two.

And it suddenly became very clear that things did not remain unchanged for long, even in the Realm Eternal.

~o~o~o~o~o~o~o~o~o~o~

Thor arrived at the top of the Avenger's Tower at the landing pad that Tony Stark had installed especially for his friend's infrequent commutes. The rebuilt Bifrost had apparently come with some new features, including a fairly pinpoint delivery point, and for a period of about two years earth had enjoyed the frequent favor of their first alien ally.

But then Thor's visits had come to a sudden stop, without warning to the Avengers or even Jane Foster. And so, unable to contact Thor or Heimdall, they sat and waited. It made sense, if they really thought about it, for Thor to get wrapped up in his princely duties. And besides, what was a year to an immortal?

Still, it came as almost a surprise when the telltale storm clouds surged over New York City once more, and the whirlwind returned Thor to earth once more.

The Tower was mostly void of Avengers at the time of his arrival, but it had long since been necessary to greet their friend with too much fanfare. So Steve and Natasha had made the trek to the landing pad alone, waiting until the whirling gusts had died down before venturing out to greet their long absent friend.

When they did eventually do so, all hell broke loose.

Or it would have, had anybody but Steve and Natasha had been there. And even then, the second visitor already had a gun angled between his eyes while the rest of the world held their breath.

Steve didn't move, didn't betray even for a moment how his heart hammered erratically at his rib cage. Somewhere, at the back of his mind, he wondered if Tasha was experiencing the same. Not that it mattered. It certainly wasn't throwing off her aim any.

Loki. Steve's photographic memory would never let him forget the face of the man that had attempted to conquer their world a few years before. Even still, the memory of that proud, vicious man did not quite match up with the one that stood before him. He seemed subdued, standing behind the shining Thunder God like a shadow. Like everything that had made him, the oceans of hatred and anger that had fed his destruction, had been stripped away and he'd been broken down until nothing remained. And then, after no more could be done, somebody had stepped in and pieced him back together. It made him look younger. And at the same time, older too, if that was even possible. But now that he let his eyes slide away from Loki for a second, he realized that Thor's countenance bore much the same look.

"What is this, Thor?" Natasha was speaking now, her voice held level in a way that defined her most frightening interrogations. "What is he doing back on Earth?" She let a bit of emotion slip in that word, sharp enough that most men would have turned tail and run. Loki didn't flinch, but didn't even try to meet her eyes.

"I apologize, my friends," Thor replied, trying his best to reciprocate the calm tones (which was a major accomplishment, as far as Thor was concerned). "Much has changed in the past months, on both of my home realms. But the Earth is in danger once more, and there is no time to rekindle old battles."

"Old? Thor, buddy, but if you'll recall four years ago, a certain someone nearly flattened Manhattan. We just finished making the major repairs." The well-familiar voice broke into the conversation as Iron Man took a place on the landing pad beside them, taking a cue from Natasha and aiming all arsenal in Loki's direction. The man only watched them impassively, still not meeting any of their eyes but not looking away either.

"You are not listening," growled Thor, his patience clearly wearing thin. Loki did respond now, eyes flashing up to Thor. "There is no time to…"

"No, Thor, they are correct." Loki spoke up now. Thor looked at him with half-annoyance and half-horror. "They have no reason to trust me, and there is no time to waste in this idle prattle." He stepped forward in a fluid motion, arms raised. Instinctively, all but Thor took a step back, preparing for battle. But Loki made no move to attack, halting just out of Natasha's reach holding himself in a sign of surrender.

"Uh sorry, but no," Tony said, "Last time you willingly surrendered, you nearly face-planted the hellicarrier into the ground."

At this, Thor too stepped forward, placing one hand on his brother's shoulder. Loki didn't recoil like Steve had expected, considering their interactions from the last time they both visited Earth, instead shooting his brother with a strange mix of annoyance and worry. The two shared a look, an unheard conversation passing between them, and then to everybody's surprise Loki visibly backed down (although, Steve noted, stepping not again into Thor's shadow, but directly to his side).

"Shall we adjourn to the cells then, my friends?" Thor asked. There were so many emotions wrangling his voice at that moment that Steve was completely at a loss for words. This was Thor for heaven's sakes: the indefatigable god who wore his heart on his sleeve, incapable of insincerity or dishonesty. What had happened in the past year to make him sound like that?

"Sure, we'll just leave your bro there, and we can all go for coffee. Or Schwarma. That's the tradition, right?" Tony was speaking in that lighthearted tone he only used when freaked out of his mind.

"Not this time, I fear," replied Thor simply, nudging his suspiciously complacent supervillain (ex-supervillain?) brother toward the entrance of their tower home, "I will be staying in the cells too, until you see it fit to release the both of us."

"What? But…why?" asked Steve, "You're not a prisoner, Thor, you're our friend."

"Aye, but I am the King of Asgard foremost," he replied, "And it seems ill to me to treat my younger brother and advisor, who has come on my request, with anything less than the comforts that I would take myself." In the four years of knowing Tony Stark, Steve had never seen anything shut him up so quickly or effectively. He would have teased him if he wasn't in a similar state of shock as the two gods swept by.