He waits for her to telepathically contact him in Fairyland.

Ready.

He flies towards the court.

There it is. Cute little fairy buildings with cute little fairies. They don't notice him.

But they might, right, and they might pretend—

Even though he's super undetectable he'll still be sneaky and watch the court from a distance to see if anything obviously indicates Thorn's there.

Not from a distance, no.

Okay... sneakily approach the court...

If Thorn is here he's inside.

Ugh. Okay. He'll pick the closest building and peek through the window.

Food prep area. A fairy is fixing salad things.

He'll look around for any rooms and things and if Thorn's not there move on to the next building.

Thorn is in fact here, having some fun with his consort. It's genuinely ambiguous whether the consort is having any fun.

Oh gods oh gods oh gods he steps through the door and tries to erase that horrible horrible image from his mind—

Do you know if Thorn's—partner—is okay with all of this—?

I think she's having way more fun than most of his vassals but possibly not every minute of every day.

I suppose when one's thoroughly immortal and has healing, he sends, some queasiness leaking through.

She does seem to kink on it on some level, it's inconsistent with Thorn's proclivities to be forcing her to act it all the time.

I... see.

...I really don't want to watch this.

You can go back later.

Yeah, I think I'll do that.

He finds a sufficiently hidey spot and... hides. Meanwhile, he'll look at what fairies he can spot and start figuring out their kind magic (this is so much easier than his world's magic to understand, it's a great change of pace).

Varies a lot. That one can hear from great distances. That one grows berries from her antlers that have an especially strong food claim.

And all of them potentially know his name.

...is Thorn likely to take a while?

Maybe.

Okay so he'll sneakily sneak around and start looking for other fairies and their kind magics and specifically anyone who might detect him.

None of the fairies present have particularly detecty magics.

Okay. Good. Yes. Whew.

He informs Promise of this.