He's not sure how to take it, at first, that the cat is rather large. Sort of Hiccup-sized. The Hiccup he's used to, rather than the Hiccup who's crashed-landed in Wonderland — but he doesn't know about that, yet. It doesn't distract him from the noise the cat-creature makes.

Perhaps this is a cat from... a very strange island. This one is a very strange island. Is it from here? Or is it stranded like him?

Toothless makes a quiet noise back, trying to relay calm through an even rumble. Sort of how he would greet a strange dragon, if he'd found one in this situation instead of a bizarre cat-thing that stretches his knowledge of all cat-things.