Mist

Mist lives a normal life. She has a normal job, a normal boyfriend, and a normal apartment in San Francisco. She never thinks about her past if she can help it.
She survived. That's the end of it.
But then a snowy winter descends upon San Francisco. In June. And in quick succession, Mist is attacked by a frost giant in a public park and runs into an elf disguised as a homeless person on the streets . . . and then the man Mist believed was her mortal boyfriend reveals himself to be the trickster god, Loki, alive and well after all these years.
Mist's normal world is falling apart. But thankfully, Mist isn't quite so normal herself. She's a Valkyrie, and she's going to need all her skill to thwart Loki's schemes and save modern Earth from the ravages of a battle of the gods.

"Krinard's background as a romance novelist lends her an ability to write well-defined, multi-dimensional characters who help this story stand out in a crowded field." — Publishers Weekly