Ilona Andrews, 2013.
This is the first of the Innkeeper Chronicles, a free online serial, though I read it in paperback. I enjoyed it, though not enough to read the second one.
My favourite bit was when the protagonist goes to Costco – people in paranormal novels do not generally do enough mundane things.
There was something almost serene about walking through Costco … Maybe it was the feeling of plenty. Everything was supersized. … It was a false but pleasant feeling of buying a lot at once and getting it at a good price. I could buy ten enormous jars of peanut butter and stuff it in the back of my car. My home was a battleground between a surly werewolf and an arrogant vampire, and a murderous alien was trying to kill us, but I would never run out of peanut butter again and I would get it for a steal, too.
The alien attack in Costco and the help from a bystander is well done, too.