I’m beginning to get a sense that the main character of Mr. Ryder is a metaphor for a part of our minds, whether it be memory or regret or conscience or such.
In another small episode, we get the inner thoughts of two different characters, and this, from the absent first person narrator. Since the other characters seem to be very familiar with Mr. Ryder and his memory goes from complete ignorance of an event to detailed memory, this seems to me a plausible explanation.
The Lost Children: A Charity Anthology