Okay, so it's blurry, but I did manage to get one photo of Mouse. There should be more--and better--pictures to come.
I left the poor critter by himself for a while and then went back in to give it one more try before calling it a night. When I opened the bathroom door, he was hiding behind the toilet and hadn't eaten a thing. He was also looking wildly around the room with nervous, darting glances. I felt bad for him and thought maybe I'd try singing a little: sometimes that seems to calm cats down. After a few seconds of "Quando miro quel bel ciglio" (damned pretentious, I know, but it was the first song I thought of), he stopped looking around so much, started blinking, and relaxed a bit.
After a couple more songs and a little episode in which he withdrew to the other side of the toilet, he started approaching me while I was singing "The House Carpenter" (awful, hellfire-and-brimstone lyrics, yes, but it has a lovely melody. Maybe that's why he liked it.). By the time the ship started to sink, Mouse had inched tentatively into my lap, one paw at a time, and started purring.
For a couple of hours, he wouldn't let me put him down. In fact, he would only eat his dinner when I pulled it into my lap with him. I brushed him for a long time; he likes that a whole bunch, and rolled over onto his side so I could brush his stomach. We played with a feather wand (his favorite toy, his foster mom said) for a few minutes, but he wouldn't move off my lap to chase it. I also couldn't get him to shift long enough to check out his cat bed, so I eventually gave up and decided to test him out in my bedroom.
He was initially very freaked out by the new room, but is now sleeping quite contentedly on my bed, so I guess he might be staying with me in here tonight, except for a short stint in the bathroom while I take a shower.
All in all, I'd say it's gone well for a first night. I'm pleased with both of us.