He's in Absalom, it seems and if something's a little off - if there's a building missing from the skyline here, or a new addition there, or - yes, that old fort outside the city walls definitely had one fewer tower last he can remember - well, there's an obvious hypotheses.

Huh. That wasn't supposed to happen. Maybe once he figures out what went wrong, he can be the first wizard to crack interuniversal travel. 

In the meantime, he'll hop over to his tower at Diobel and see what's there. 

The spot in the general vicinity of Diobel where he has a tower in his universe is empty.

There is a tower about a hundred feet north, though. The ley line's a little out of position too.

Alright. He'll wander over. What kinds of spells does this place have up? 

To his arcane sight, absolutely none!

And the ley line runs through this other tower?

Of course!

Yeah no it's magic. Does True Seeing get him anything? 

There's a thin slit in one of the walls, and the words "LEAVE A NOTE" in Azlanti painted above it, all masked by an illusion - other than that the tower's stone exterior seems to be real. There's a scrying sensor over the door, and an invisible stalker hanging out nearby watching him.

He waves at a stalker, then conjures some paper and ink (he's also carrying some, but it would be undignified to be seen needing to reach for them). "I am a traveler from another universe. In my world, I live about a hundred feet down the hill, and since we're counterfactual neighbors, it only seemed polite to call – Élie Cotonnet." The note's in Azlanti. He'll deliver it by mage hand and head back to the city. 

Élie has barely made it back to Absalom when he notices an illusion spell - invisibility, looks like - headed in his direction.

Ooooh, does it have a letter? 

It does! Carried an imp, which volunteers to wait around for a response.

Élie Cotonnet,

That's a rather extraordinary claim. Do you have anything which might support it? I beg you to pardon my skepticism, if it's unwarranted - I get a great number of letters making extraordinary claims, and most prove meritless. If you have no evidence for this particular claim which can be conveyed in writing, but wish to prove that you are at least worth an hour of conversation, you could inscribe half the spellform for a limited wish in a return letter - regular ink would suffice, as I hardly need it for my spellbook.

 

-A

It's been a very long time since he's gotten a letter signed A. 

....It could be her. Alfirin did choose the location of the Diobel tower. The handwriting – might be similar, it's hard to say. 

He inscribes half the spellform for Wish. If it's her, she'll know. 

The imp takes it and teleports away.

And, a moment later, quickened disjunction

- So it's not a polymorph, nor an illusion, just a man who is not undead and by most reasonable standards too young to know wish.

"OK, you have my attention. Did someone set you up to this or is it real? I will know if you're lying, I don't recommend it."

"Alfirin," he says agreeably. "Or do you prefer whatever name you're going by in this life? Either way, I certainly know better than to try lying to you."  

"...this life?"

If he's lying he's very good at it. And he knows - or at least guesses - that she plans to reincarnate. And said it out loud. In the middle of a crowded street.

"Perhaps we should have this conversation somewhere else."

...she hasn't reincarnated yet? Or, more likely, she doesn't want him to think he knows she's a reincarnation of an ancient evil witch. In any case – 

"Agreed. I'm sure you have something more private than a standard Private Sanctum?"  

If she agrees she's confirming that something he's said spooked her. And the only thing he's said is implying that in his world she's lived multiple lives already.

But if he's legitimately a 9th circle wizard - well, that would be surprising enough in its own right that being from another universe is - still extremely unlikely, but maybe not disqualifyingly so.

"I don't usually take strange men there, but I can make an exception for one as strange as you. Do you have a plane shift ready?"

"Certainly." 

Well, she's not going to hand him a tuning fork, but he can bring them back when they're done talking, if they're both still alive.

The demiplane she shifts to is a bubble of force, filled with magical darkness to bring the intense glare from the bubble's exterior down to merely the brightness of a sunny day.

"Alright, master Cotonnet. You clearly have me at a disadvantage. You started this conversation. What do you want."

"You know, I'm not exactly sure. I'm from the year 4712, I was doing some experiments with inter-universal communication, and the answer to that question really depends on where and when I seem to have found myself. 

I really do live about a hundred feet down the hill from your tower. You picked the location, actually. The version of you I know is – well, among other things, she's a very old friend of mine."

"Very old friend? You implied that she lived multiple lives, are you also immortal?"

"Goodness, no, I'm thirty-two. But the time we've known each other has held more than its fair share of happenings –  " sometimes literally – "and besides,  you really did reincarnate into the body of childhood friend of mine, which I think counts for something. – I forgave you for that, incidentally. Even if you could have told us sooner."