A minute later, glasses on, I found my suspicions confirmed. The newest cat toy was a dead rat, grey in color, fairly young. Now, since Circe doesn't go outside, and I know who the ratter in the household is, I realized that Ming has finally accepted her completely. He brought her a rat, like mama cat would. He leaves rats for me and the neighbor lady next door, and now he's brought one home for his fluffier counterpart.
This was confirmed a few minutes later, when Ming stopped by, took a couple swats at it himself, and moved on. I let her play for a few minutes, then took Mr Rat out to join a succession of his kin in the compost pile.
If I were to start letting her out, I don't doubt Ming would train her up in the best rat-hunting techniques.