In all the years that they oppose one another utterly, across the decades they spend as the best of enemies, among all the things, bright and cruel, that they say to each other... Erik and Charles each keep back one thing. One thing that each of them will never tell the other.
Erik will never tell Charles that in the wreckage of the submarine, hearing his own ideas spill from Shaw's mouth, he lost faith in everything he thought he believed.
He discovered that he really was Shaw's monster, his ideology handed down directly from his loathsome creator.
"If you're in there, I'd like you to know that I agree with every word you said. We are the future," Erik told Shaw, told Charles.
His voice sounded sure, but in his head, in the inviolable confines of the helmet, he was screaming.
How could he hate Shaw so much, and still want to live in the world Shaw sought to make?
He saw everything Charles had been trying to tell him. As he released the coin to float into the air, he understood.
The path he thought he had chosen for himself was the path Shaw set him on, all those years ago, and it would lead him to ruin. He would become the man he despised. Like Shaw, he would kill and destroy while claiming the ends would justify the means. But his ends would make a world with no greater hope in it than more death and destruction.
Having extinguished the human race, what would mutants do but turn against one another? Like every other new species before them, they would begin in conquest and end at each other's throats.
He remembered a hundred ways Charles said it, not only in their portentous conversations over chess-- "New ideas are like chessmen moved forward. The pieces may be beaten, but they can start a winning game"-- not just then, but casually, every day, the way he lived it.
Start as you mean to go on, Charles had said with his funny little grin over breakfast, teasing Raven into a smile, Do what you can, with what you have, where you are when Hank worried that his feats of engineering weren't good enough, It's not a mistake if you learned something from it for next time, to Alex when his powers slipped out of control, Anything worth doing is worth failing at, when Sean fell like a stone from the window.
Erik took little notice at the time. It was all trite and glib, meant as comfort for children. Pompous. Rather silly, really.
At the end of a long day training in the woods, sitting side by side on a fallen log, passing water back and forth, Charles nodded toward the kids as they showed off their powers for Moira, and told Erik, This is a world worth fighting for. At the time, Erik only heard it with the hope that Charles was beginning to agree with him, but now he saw the truth.
Charles had never thought it would be easy, he had never pretended it would be soon, but he saw hope for a future that could be forged in peace, and he believed it was worth any struggle, any sacrifice, to get there.
Maybe he was mistaken, but he truly believed it was a mistake worth making.
Charles believed that Erik had it in him to be a better man than Shaw. And maybe, if they'd had more time... maybe Charles might have even helped him make it true.
But even as he sent the coin through Shaw's skull, Erik thought maybe this could be his last failure. He couldn't stop himself from ending Shaw's life, but he could stop himself from following Shaw's path.
He could never stop fighting, but he could use his strength to protect his own, to secure and to build. They could make a place for themselves in the world, and day by day and year by year, as every assault from the old race was turned aside, as more of them joined together to defend one another... slowly, painfully, but inevitably, the world would change.
As the coin dropped to the ground, Erik thought perhaps he could promise Charles that the blood on that coin would be the last blood Erik would ever shed.
Then he turned to re-enter the world, and felt the weight of a thousand weapons, all moving to target the beach.
He saw Charles pulling himself unsteadily to his feet, saw the broken look on his face when Charles met his eyes. He had severed more than he knew when he put on Shaw's helmet to shut his friend out. Charles might never trust him again.
And how dare he turn that disappointment on Erik, while behind him, his beloved humans prepared to murder them all in cold blood.
Even if they knew Charles for who he really was, even if they recognized him as their best ally, they wouldn't care. They were afraid of what Charles could do, afraid of what Charles was, and they would destroy him before Charles even acknowledged the threat.
Erik felt the shudder of gears turning inexorably as the primitive race primed their guns and began their countdowns. They issued no declaration, no notice. Charles would never even have the chance to face his fate. They were turning on Charles in utter treachery, perfectly willing to shoot him in the back.
Erik stepped out of the wrecked submarine, and onto the path Shaw had marked out for him.
He called to his brothers and sisters with the bitter ring of truth in his voice. He looked at the missiles arcing toward them overhead and knew the world to be cruel and mean and small. This world would never change. It belonged to men like Shaw, and the only choice was to rule them, or to be ruled by them.
If Erik weren't here to stop these bombs, Charles would die on this beach, and his dream would die with him.
When the shot struck, when Charles folded to the ground, Erik collapsed at his side. And there lay the final proof. The coin moved or it didn't move, what difference did it make: the bullet found its mark, either way.
It's the lesson he carries forward every day after that. There is no mercy.
Even knowing that, fixed and certain as the iron in his blood and the marrow in his bones, Erik will keep his one secret. He won't believe in grace, but he can never bring himself to break that heart again.
He will never tell Charles that for those few moments, the choice unmade, the coin in the air, suspended between rage and serenity, Erik believed in him, and knew peace.
Charles will never tell Erik that in those scant few seconds on the beach, after the bullet struck and he fell to the earth, in the moments before Erik came to him and used his power to pull out the bullet... before the metal left him with a sickening scrape against flesh and bone, Charles could still move his legs.
His heels dug into the sand. His toes flexed inside his boots. He felt the drag of his feet and the spasm of his knees. He felt the pain of the wound.
Then Erik drew out the bullet, and Charles felt nothing.
Charles is no saint. There will be so many times he'll be tempted to strike out with that truth, to shatter Erik's certainty.
You want me to join you, but it wasn't an enemy who struck me down; you did. Then you took out the bullet as if that could undo what you'd done. And you only ensured that I can never stand beside you.
There will be times he looks up-- always up-- into Erik's face, shamed by how badly he burns to say it.
He never will.