Back before I was really even finished with In Pain and Blood, I kept getting pieces of story that happened after the main novel, but which also didn’t fit into the novel. I still get odd bits here and there, but nothing pulls as strongly as An Unexpected Gift did.
An Unexpected Gift is 21k extra to In Pain and Blood. It’s set a few weeks after the main novel’s epilogue and will have spoilers as well as a high chance of vagueness in detail for those who haven’t read In Pain and Blood. It is not a standalone.