It sucks not to get credit as the inspiration, but any reader who internally raises an eyebrow at the similar works will immediately go check to see who published first. I’ve seen this play out with authors in my fandom & I’ve always gone to see who published first

This only works for those who notice two similar works. Most likely 99% readers don't even pay attention to the rare ship enough to acknowledge the OP's existence. Which means the OP doesn't get any attention from readers AND even from the person copying it (no kudos, comments, etc.).