The fifth stone clicked into its place on the gauntlet.
The ground shuddered under them; debris rained down. Strange wearily raised a hand and dropped them through a portal, onto a side of the planet where the cataclysms would take an hour to reach them.
"Are you okay, Mr. Stark?" said Peter Parker.
Tony was sitting in the shreds of his armor, staring at Titan's ravaged horizon. He was grimacing, but not in a I'm-bleeding-out sort of way. He glanced at Peter, nodded jerkily.
Then he turned to look at Dr. Strange.
"Okay," said Tony, "assume for a second I'm not an idiot."
From the expression that flickered across Stephen Strange's face, he was going to have a hard time with that.
"That didn't fit." Tony's armor swam across his chest again, as if preparing for yet another fight. "You said - you said one in fourteen million. I have an understanding of what it would look like to fight a battle which we lost 14million times to one. I have worked on engineering projects that needed to have a failure rate of one in fourteen million. A fight with those kinds of odds - it looks overdetermined. It doesn't look close. That fight - we lost. But there were several times -" he shot a glare at Peter Quill - "where we nearly won. If you'd managed to get a portal around his hand. If we'd had a weapon on hand with which to hack off his arm. If Mantis had held on a second longer - if, if, if, if - that's not what 'one in fourteen million' looks like. A fight we had those odds of winning shouldn't even have been close."
"It wasn't," Strange said. "If I'd foreseen that killing Quill would have saved us, I'd have done that. We weren't close. Cutting his arm off would have failed. Getting the gauntlet off would have failed. Keeping him under and destroying this planet would have failed. We lost every time."
"Well, Debbie Downer," said Tony, "maybe you could have told us that so we coulda, I don't know, headed back to Earth to -"
"What do you mean nope -"
"We can't beat him there either."
Tony stood up, half-armored, and took two slightly shaky steps towards Strange. "I don't believe you."
"You handed him the time stone. You sold out - everything - that fight was closer than it should have been - maybe you're not very good with your magic rock or maybe you're lying, but -"
"We needed one thing from that fight," said Strange. "We got it. If we'd spent prep time having this argument, we wouldn't have. It's over, Stark. We lost. Half the universe is going to die. And then we're going to undo it. That requires you, alive."
"Wow, how flattering. You could have told me to not fight him, I'd be alive and we wouldn't have given up the stone -"
"And you'd die in five minutes," said Strange, "when he snaps his fingers. You were in the dying half. Inconveniently, we need you. Our objective in this fight was to convince Thanos to spare you."
"Couldn't you have done that yourself, with the time stone?" asked Peter Parker.
"It's trivial to get Stark through the fight alive," Strange said impatiently, and to Tony, "We need Thanos to micromanage his mass slaughter to leave you out of it. I couldn't have asked it if you hadn't been there; he wouldn't have granted it. I couldn't have asked it if we hadn't attempted all the ineffectual things we did; they earned his respect. You had to try to stab him. You had to look at him, believing you were going to die. And then I had to ask for your life. That's what one in fourteen million looks like. It doesn't look overdetermined. It's a random set of chances any of which could have gone wrong and knocked us off the only path we had. Four minutes left, now. But you'll live."
"Oh," said Tony.
"Uh," said Peter Parker, "do you happen to know who all will die."
"We'll all die," said Strange. "Except Nebula, which is important because, seeking her out, Thor will find Stark."
"You'll die temporarily," said Tony, "you'll die temporarily and we'll get you back - I'll get you back - we're gonna undo it, we're all set for that -"
"No," said Strange. "This fight - even guiding it with foresight, I saw a hundred variants where you died. Rocks, weapons, bad luck - if that sword had hit you an inch higher up you would have died too quickly for Thanos to finish his speech and give me an opening to ask for your life. You might undo it. But from here, we still usually lose. I will tell you everything I saw. But that might not be enough."
"One of us," said Tony, "has designed machinery to these kinds of fault tolerances before and it wasn't you. Cut the lecture and get to the 'everything you saw'."
The ground rumbled. Several people jumped.
"Thanos will murder trillions including us before the moon collision kills us," Strange said reassuringly, and then he explained the plan.
Tony held Peter's hand. "I've got this," he said when Mantis gasped and Peter flinched. "We'll avenge the Earth and then we'll retroactively have managed to protect it, same as always, just out of order, I've got you -"
"I know you do, Mr. Stark," Peter said, and turned to ash on the wind.