I never thought I’d read an Ilona Andrews horror story, but here you go…
Apparently many years ago, IA wrote a slasher-style short story for a nameless magazine’s Horror/Halloween issue, but it didn’t get published. And they resurrected it just now as a treat for their blog readers.
There are a few spoilers in the blog post, but you can skip them if you wish and go straight to the link to the story near the bottom of the post.
And it is kind of fun, because it’s possible to recognize some elements that carry through to other books of theirs.
Link to blog post for Only Forever: https://ilona-andrews.com/blog/trick-and-treat/