The speaker was an old man with well-combed silver hair and eyes glittering with mirth snapped his fingers and Tony flinched at the sound before finding himself in the chair across from the man. Natasha appeared in the one next to him, shocked but looking ready for a fight.
"Make yourselves at home, it's not like anyone's leaving any time soon. So how's the stone been treating you?"
Tony was quick to reply. "Well, I just got here, you'd have to ask Nat over there."
"Who even are you?" asked Natasha, "And how did you get here?"
The newcomer smiled knowingly. "Just call me Stan, and I'm here to make you a deal."
"Wait, do I have to sell my soul? I'm pretty sure it belongs to the stone we're all stuck in, or Pepper," said Tony, "She would probably march in and take it back before you could even offer, just to warn you."
The man grinned. "Don't worry, you won't owe me anything. And Pepper isn't one even I would mess with." Tony visibly relaxed.
"What kind of deal are you offering? And, again- how did you even get here?" inquired Natasha.
Stan sighed. "Like the two of you, I am dead. But you could say that the stone and I go way back, and I don't feel like moving on quite yet. Say hello, stone."
There was a deep rumbling that gently shook the pocket of existence that the group was stuck in to its very core. Tony almost jumped out of his seat while Natasha shuddered. Stan merely smiled fondly.
"Now, what is it that the two of you want most? The stone is willing to release it's grip and let you move on to the peaceful afterlife that you've more than earned by now. If that's what you want, then you can follow me."
Natasha sucked in a small breath before speaking. "I doubt that where I would wind up would be any more pleasant than this, if it goes by what I've earned and the lives I've taken."
Tony looked at her incredulously. "Natasha, you gave up your life to give half of the universe a shot at returning. Long before that, you had whatever debt you think you owe to the world paid. If there's anyone that deserves moving on to something better-"
Natasha abruptly cut him off. "It's you. When you showed up, I knew it. We won. Thanos is gone, but you had to have been the one to sacrifice yourself to end it."
"Nat, I can't move on. I left it all behind, and not so that I could escape to a goddamn afterlife I didn't know existed. So Pepper, Morgan, Happy, Rhodey, Peter, the team, so everyone could live, even if that meant I wouldn't," he shot back.
"I can't go either." she said softly.
Tony looked back at Stan, who had been watching the conversation with an observant, soulful look in his eyes. "It's settled. We can't go on, and we want- scratch that, we need a way back home."
The old man nodded. "I suspected as much. There's so much fight in people like you, and it looks like neither of you are done fighting yet. All you have to do is prove to the stone that you should go back. That the world will be better off with you back in it, that the legacy you have left isn't enough to keep it going. If you choose to rise to this final challenge and fail, the stone will claim your souls. It doesn't often come across such bright ones, but it would like to keep yours as company, from what it tells me."
"Why doesn't it just hold on to yours?" blurted Tony.
"There was no bargain with me. Just an old friendship allowing me to give you this chance, should you accept. I'm warning you though- no takesie-backsies." said Stan, eyes glinting mischievously.
Natasha nodded grimly. "I have nothing left to lose. I accept."
"I'm with her on this, we have friends and family to return to. I'm in." said Tony.
"Alright," said Stan. "Before we begin, there are a few rules. You will be able to interact with the world as if you were ghosts. Unfortunately, you cannot explicitly or obviously draw anyone's attention to the fact that it is you. Subtle actions, hints, and clues are the absolute most you can get away with when interacting with a specific person- they need to figure it out on their own, or not at all. Second, you only get a specific amount of power to use daily. The soul stone will only allow you to draw so much from it, but you will get better as you use it more often. And finally, I'm sticking around to offer some guidance and give you warnings as needed. Are you ready?"
Natasha and Tony made eye contact with each other before looking over at the man and nodding.
"Good luck, and see you around!" he said before waving a hand. For the two dead Avengers, the world spun around them at dizzying speeds before disappearing altogether in an orange haze.