Welcome to my new Marvel story. I've been working on this story for months but have finally decided to start posting it.

Title: Fateful Choices

Author: the-writer1988

Rating: T, this will rise to an M later.

Summary: Tony made the choice to make the sacrifice play and was lost. Steve chose to close the portal. Both lived to regret it. Dark AU.

Characters: Tony Stark, Steve Rogers, Natasha Romanoff, Clint Barton, Pepper Potts, Happy Hogan, James Rhodes, Thor, Loki, Thanos, The Other, Chitauri, Nebula, Gamora, Peter Quill, Groot, Rocket Racoon, Drax, Nick Fury,

Disclaimer: I do not own Marvel. Disney does.

Notes: This is a canon divergence fic from the end of The Avengers where Tony takes the nuke through the portal, but he doesn't return. This fic is long, covers dark themes and the rating may rise in future.

I would like to thank doodlegirl1998 for her advice and help with this fic so far. Without her constant advice, this fic wouldn't be in the state it is today to be able to post. So, THANK YOU!

Prologue

"Stark, do you hear me?" Nick Fury's voice reverberated over his com channel. "You have a missile headed straight for the city."

Tony grimaced, wincing as another hit from the Chitauri weapon bashed down against his head. Protected by the armour for now, he wouldn't be able to stand repeated hits like this. He had to get out of this mess he had gotten himself into. "How long?" He fired one of his repulsors at the advancing Chitauri warriors in an attempt to fend them off, trying to give himself a chance to escape back into the air.

"Three minutes max. That payload could wipe out midtown."

Not long.

It wasn't a good time frame but Tony did not hesitate. Fury contacted him because he was the only one capable of doing anything about an incoming missile. "JARVIS, put everything we got into the thrusters!"

"I just did, sir."

The suit thrusters engaged and Tony swooped past the Chitauri and back into the air. He flew out of the city and out over the water, scanning for the emission signature of the missile. It flew past him at speed. Firing the thrusters on his hands to swiftly bring himself to a stop, Tony twisted in mid-air, engaging the thrusters once more to shoot off after the missile.

In the space of a few seconds he knew where to put the missile. It may have a homing signal on it but the Iron Man suit was powerful enough to counter it and sway the missile onto a different path. The trajectory of the missile seemed to have been locked onto his tower. He could only nudge it so far off course. It would be a near-miss…

Designing the suit the way he had, Tony had ensured he could deal with any problem. He had never imagined he would ever use it for this however.

Then Natasha's voice came over his earpiece.

"I can close it! Can anybody copy? I can shut the portal down!"

Shit! Don't close it yet! I need it!

Steve Rogers voice answered back. He was the defacto head of the team. It was his call. "Do it!"

"No, wait!" Tony interrupted, wincing as he sped faster towards the Tower, beginning his flythrough through the streets of Manhattan.

"Stark, these things are still coming!"

He couldn't lose his cool now, not when he was about to do something incredibly stupid and so… self-sacrificing. Oh god, he was going to die. Despite the fear that crept up into his stomach as the thought blossomed into his consciousness, his thoughts co-operated with his mouth and allowed him to quickly explain exactly why he needed the portal to remain open for just a tiny bit longer. "I've got a nuke coming in. It's going to blow in less than a minute." His voice quietened as his eyes focused upon the portal just ahead of him.

"And I know just where to put it."

Catching up with the missile, he swept underneath it, placing his back against the bottom layer of it, as he lifted his arms to grasp onto the missile itself. A magnetic pulse enabled him to attach himself to the missile with not only his hands but with his back as well.

As he directed the nuke towards the portal situated above his tower, Steve's voice came over the com-unit.

"Stark, you know that's a one way trip," said Steve, sounding solemn.

I know but there is no other way. He didn't reply to Steve. He didn't need to. The Portal wasn't closing. Tony swallowed. "Save the rest for the return, J." There was still a chance he could make it back but the suit hadn't been built with space travel in mind. If he ever got back to Earth, he would have to incorporate that particular feature into future suits.

"Shall I try Miss Potts?"

Tony thought for a few brief seconds. If he was never going to see her again he wanted to hear her voice one last time. Oh so very much. "Might as well."

Pepper's beautiful face appeared in his visor. As the call began, he pulled up and began his ascent, skimming the side of the tower, narrowly missing careening into it. He shot up, past where Agent Romanov stood with Dr Selvig, and flew straight into the portal.

The call he had been making to Pepper broke down, the signal lost. JARVIS' voice trembled and he faded. The visor darkened and he lost power to the suit. The clamps broke and Tony floated away from the missile as it headed towards its trajectory.

Ahead of him he could see thousands more Chitauri ships heading towards the portal and a large station that seemed to be their main base was rotating slowly in space. The stars around Tony began to spin.

He couldn't breathe. The suit was failing him. His head felt light and dizzy. But he held on, knowing that he was dying but he had to make sure he had succeeded.

The missile reached home and a large, bright flash spread out across the stars as the station broke apart, scattering into pieces. He saw the Chitauri fall, as if the station had been the one thing controlling them…

And then…

He closed his eyes and knew no more.

To be continued...

Please let me know what you think!

I felt it prudent to start this story off with Tony's sacrifice. I think it is important to show his thoughts and feelings. Tony never expected to return. He made the ultimate sacrifice play. In this fic... he doesn't fall back through the portal. The fic takes a different path from here onward.

More will be posted soon :)

Until then,

the-writer1988