I think it was gokuma who first suggested this: Erik is stalked on Genosha by a child version of Charles. Warning: Character death.

The child is small, almost mousy-looking, with soft-looking hair and brilliant blue eyes. He can't be more than about eight or nine, and when he first approaches Erik in the gardens, looking small and innocuous and almost ethereal, Erik should balk at him or demand to know from whence he came - he doesn't recognize him from around the palace - but something compels him to simply let the boy stay.

Erik doesn't speak to him at first, nor does the child seem compelled to talk. For three days, they simply seem to inhabit the gardens at the same time, until finally, the boy says softly, "Why do you come here every day, Mister?"

Erik's eyebrow quirks. "My name is Lord Magnus," he tells the boy gently; the boy's face remains impassive, but if Erik's not imagining things, he thinks he might see just a hint of a smile. "Why do you come here?" he asks, deflecting the question away from himself.

The boy's eyes are so, so bright, he realizes. "I come here because of you," he answers, and Erik blinks, not expecting this. "You just seem so lonely and sad," the boy continues.

Erik looks down. "I don't think I'll ever be happy again," he says honestly, half to himself. The hand on his shoulder is small and warm, and he isn't sure why he doesn't shrug it off, but he doesn't.

After this carries on for some time, Erik finally demands to know the child's origins; he begins to ask around at the palace, but nobody seems to know. Everybody has been giving him quite a wide berth already, ever since Charles' death, and this seems only to add to the small smiles and worried glances that Erik sees out of the corner of his eye.

Once, he tries to feed the child, to demand that the boy comes to the kitchens with him for a hot meal, but the boy steadfastly refuses. However, he does trail after Erik on an occasion as he takes long strides to get to his private quarters, which he is, for some reason, embarrassed to let the boy see when they seem so stuffy and lived in; he goes about opening doors and windows and tossing clothing into wayward corners of the rooms, and the boy just stands there watching him, calm as always.

Eventually, the child walks towards Erik's bed, reaching out and strokin the wine red coverlet with small, pale fingers. "You miss him, don't you?" he asks, and Erik jumps, because it's like the boy can just tell that Erik painstakingly sleeps only on one side of the mattress every night, just in case ... well, just because. "It's okay to feel sad," the child continues. "But not all the time, right?"

Erik smiles ruefully, because this seems like such matter-of-fact, generally useless but ultimately endearing Charles logic. "Probably not all of the time," he concedes, and the boy smiles slightly.

"Mister, what are you doing?" the boy asks. It's several weeks later, and Erik has taken to cleaning and sharpening and polishing the knife that Bucky Barnes murdered Charles with obsessively. The boy's eyes are unusually critical when he sees the Master of Magnetism perched on the bed, staring at the long, silver blade.

"It's none of your concern," Erik tells him, more sharply than usual. He looks up, and his weary eyes bore into the boy's young, concerned ones. "Go away," Erik says, making a shooing motion. "This is not something you should see."

The boy flees, and Erik does not see him for a long time.

He decides to do it in the gardens, because then he can stare at Charles' name carved into the large stone centerpiece while he does it, just in case there's any doubt as to where he wants to be in the afterlife. For some reason, he isn't surprised to see the boy again, for the first time since he told him to leave.

"He doesn't want you to do this," the child says sadly. He doesn't touch Erik this time, but looks as though he wants to. "He very much wishes you could learn to live without him."

Erik frowns at the weapon in his lap, the blade gleaming. "I cannot," he says simply. "It is too much. I just need to go where he is. This world is not for me anymore if it is not for him."

The boy's face crumples. "I'm sorry," he whispers; and then, before Erik can stop him or move out of the way, he throws his small arms around the older man, hugging him tightly. Erik is pretty sure he hears the child murmur, "I'm sorry, Erik," but then the child is pulling away and kind of bows in front of him a little. "Quickly," he says softly, and watches Erik heft the knife without using his hands. "Do it quickly, so there won't be much pain."

"Thank you, Charles," Erik tells him, and then he closes his eyes, and plunges the knife into his chest.