I've been thinking about Backrooms lately. I even kind of like themes like dreamcore and such. And then I thought, what if I threw Kabuto and Noa in there?
As for Kabuto, I think he'd be more curious. At first, of course, his first thought might be, "What the hell?" It's a strange, yellowish, and unpleasant place. No furniture or people, just strange creatures on the edge of his field of vision. At the same time, in my hc, Kabuto is a curious person and enjoys acquiring knowledge.
So he'd probably quickly come to the conclusion that standing still wouldn't do him any good. He'd start traversing the levels, occasionally stopping and turning around, staring into space behind him. Because something would constantly be staring at his back.
In all of this, however, what Kabuto found most troubling would be his mind. Not the large rooms, not the silence, but the intrusive thoughts.
I think he would say something to himself sometimes.
Noa would probably advise something quite similar to Kabuto, also exploring and trying to find something...normal. She wouldn't mind the silence or loneliness. She would feel a strange nostalgia looking at these empty spaces, seeing things that seem...familiar to her. This weirdo would probably be touching the water in the levels where there is water. She would be sitting on objects, trying to piece it all together in her head.
In all of this, however... I think Noa and Kabuto would unconsciously pass each other by, wandering around, searching for a way out, or perhaps something they lost long ago.