Fishsitting a Betta

We're fish-sitting an elderly betta. He's already almost 18 months old, and this is how long they live in captivity. He sleeps a lot. It's been only 3 days. We'll have him for weeks. Every morning I'm on edge. I approach slowly. He's motionless, close to the surface. I check for bubbles. I wave my hand. I don't know if he likes me, or if he even knows me. In any case, I'm not his owner. He doesn't move. My daughter skips down the stairs. She's innocent. She has no expectations. "He's awake! Is it time to feed him yet?" And he moves. Just barely, but he moves.