A strange hallway appears around Aeslin.  She blinks, draws her wand from her sleeve in a moment, whirls, and casts to reveal any invisible creatures.

There aren't any.

Then what suddenly teleported her here?

Well, there's a good bookshelf in the hall, with a lot of books.  Whoever lives here has an interestingly eclectic taste.  And they probably aren't a magician - that book looks like a novel, and that one too...

She shakes herself; there's no time to be examining the books.  There's an open door at the end of the hall, and no magic traps there.

I look up when someone enters.  "Hey -"

And then I see her.

I jump up in shock.  "Oh!  Uh, hello, Aeslin!"

It's a bedroom with a strange human (or Elf?) in it, who probably isn't a magician, and definitely doesn't look like he's expecting her.

"Who are you and how do you know my name?"

Of course she's prickly.  But I know her; I know that she won't be satisfied with anything less than a full story (with myself cast in it as either Fellow Magician or Hapless Muggle) or else the truth.

I don't like self-inserts in full stories.  I'll go for the truth.

"I'm your author."

She stands just inside the doorway, holding her wand ready with a magic-detection spell active, her mind racing in circles around this preposterous claim that's even more preposterous than this situation was looking.

"I didn't think I had one of those... Fintel does raise the possibility of multiple universes, and of course it's common in nonmagical fiction, but Fintel barely speculated about going up a level into a higher universe..."

She shakes herself.  "Well, prove it."

I frown.  The classic example would be something like having the sun race around in loop-the-loops, but I'm thinking this setting is already pretty fragile.  (Notice that I have no idea which model of computer is on this desk here, or what year it'd say it is.)  Any other proof that'd work would be uncomfortable.

But, I shrug.  I know she won't mind it, for a reason like this.

"Okay, you asked for it."

A moment later - without feeling any magic - she's seeing the top of her own head from somewhere around the ceiling!  She tries to raise her wand arm - it raises, but with a wildly queasy sensation as she's watching it.  And her wand (which didn't detect any magic) has bent itself into a bracelet around her wrist.

A moment later, she's back in her body.  She swallows.

All right; she can't argue; she did ask for proof.

There's no way any magician could've done that without at least a dozen spells that she would've noticed.  Even if they'd changed her memory, she probably would've noticed a discontinuity in her thoughts - and if she's questioning that, then she's already at the level of Descartes' demon and might as well give up that whole thread of hypotheticals.

So he's got new magic from beyond the world - no, beyond the galaxy or universe - which means he might as well be telling the truth, and if we take Fintel's inter-universe summoning speculations seriously he sort of would have authored her anyway -

"How did you do that!?"

I smile and shrug.  "I wanted it to, and I described it, and it happened.  I'm the author."

"But how!?  What're the rules of this magic?"

"What I can think of.  What I know how to describe.  What I want to describe."

(And each of those limits have been very significant at times.)