Charles expects Erik to show up at the mansion within a few months or at most a year after the War. It's not like he's really a teenage boy, any more than Charles is. As erratic as Erik's mutation may yet be - as undeveloped as Charles' own is, now - he's seventy damned years old and Charles knows that if he's here, he's very capable of finding his way to Westchester by whatever means necessary.
If he's not here, then there's some reason he hasn't come yet.
It occurs to Charles that Erik may not be here at all, that something else went amiss other than landing nearly sixty years earlier than they meant to. That he made it here alone, made it here without Erik. It's a thought that keeps him up nights, so afraid that he's reversed things entirely, that he's gone from he and Erik being the only ones left, to it being Charles and...everyone else but Erik (his Erik, at least).
It's also possible, given the surroundings Erik would have found himself in - it's possible he did come back, and got himself ki got himself into trouble.
Charles thinks about looking for him; but it's not like he has an itinerary of Erik's travels from before they met, so there's little to no chance that globetrotting will help to find him, regardless of whether he's here or not. So instead, Charles waits for him, and waits; and the years pass.
The summer before he's due for his first semester at Oxford - not that he has any particular desire to relive his life on the same script as before, but Oxford is theoretically the path to Erik as well as to stopping Sebastian Shaw - Charles develops a tendency of taking naps in what was once his study, in that life where he raised up teenage mutants only for them to all be slaughtered wholesale with his own mind unwittingly playing the part of the showers.
Raven laughs at him for the habit, calling him an old fart. He could respond that he's been an old fart, that old farts don't sleep nearly as well or as deeply as whippersnappers like him; but he refrains.
So it is that one day he wakes up from a nap in his study with a sense that something has changed (a sense dismissed out of hand, as he's had no few false alarms in the past). He glances out the window on his way out of the room -
Then whirls around once he hits the hallway, heading back into his study so quickly that he almost trips over his own feet for the first time since the first month he had the use of his legs again.
And yes - yes, he did see it: the satellite dish is pointing toward the house.
It is not supposed to point toward the house; and as Charles stares at it, hardly daring to believe after all this time, it begins to turn back around.
Charles raises a trembling hand to his temple - he's tried to throw this old crutch, but has yet to reach that point - and reaches out towards such a familiar, welcome mind.
Oh, he thinks, and he's laughing and he's crying a little as well. Oh, darling. You do know you're not supposed to be able to do that yet?
I'd rather not have to depend on you, comes the answer, infused with a fierce joy Charles isn't sure he's ever heard from Erik. So I brought my happy thought with me this time. Before Charles can even run through what this might mean, he adds, We're at the door; come let us in.
You and I both know you're perfectly capable of letting yourself in,Charles thinks, but he hurries towards the front door anyhow.
When he throws the door open, he first sees Erik, younger than he's ever seen him; Erik, with a peace on his face Charles has never imagined.
We, Charles thinks, as he then takes in the woman by Erik's side. Us.
Charles has been deep in Erik's mind, seen Erik's most precious memories. He'd know her anywhere.
"Oh, Erik," Charles says, weeping openly now.
It's a long story; I'll fill you in later, Erik sends, at the same time that he says, "Charles, I'd like you to meet my mother."