It's certainly not the sort of architecture you'd expect to see in Gotham City, that's for sure. (Well, not outside of a few select locations, anyway.)

Even after what Frisk told him about the castle being in the sky, he doesn't quite register the clouds as clouds- it's hard to distinguish it from regular fog.

Despite the fog and Frisk's brisk pace, it's easy for the Batman to keep up with them, although he winces a little at first when the door groans. For some reason he wasn't quite expecting it. But he forgets the pain of the noise once he sees what's outside.

Grass, a stone path, a light breeze that ruffles his fur, and a lot of fog- or clouds- it doesn't sound that impressive but even from the doorway he can see a very obvious cut off at the end of the path, and when he trots down to the end of it and peers carefully over the edge, sure enough, there's nothing there.

The Batman slowly backs up until he's in the center of the path, where he pulls himself to his feet and straightens to his full height. He absently cups his chin in one hand and examines the edge. A bit of a run, and a few flaps of his wings...

He turns to Frisk, and extends a hand.

"Want to see what's over the edge?"