Fires of the Forsaken - Stephanie E. Donohue - Bog

Addie wanted a gosh-darn pizza.
Lass wanted to avoid being cooked over a spit.
Neither figured they'd end up with a one-way ticket to the end of days.
Addie did not have "getting plucked from the 21st century and thrown into a rudimentary fantasy world" on her "fun things to do at 30" checklist. Yet here she is, struggling to survive in the hellscape known as Sakar, a place where Wraiths flame-broil humans and Celestial armies wage war with each other over a centuries-old spat. Thankfully, Cheriour, the hunky commander of the human army, takes her under his wing-although he's allergic to giving straight answers. And talking.
As Addie reluctantly starts to care for him, and the rest of the Sakarians, she also learns why she was sent to this world. And it's a doozy...
The violent society of Sakar is the only home Lass has ever known, and it's been a wretched one. She has spent her life being tormented and twisted into an inhuman hybrid by the Celestials and hunted by the humans who fear her. But she finds solace with a cocky, blue-eyed boy who comforts her, even after she accidentally slaughters innocents.
As Lass struggles to control her volatile powers, she slowly transforms into the monster the humans believe her to be. And even the boy she loves is in peril...
At the end of time, there is only fire. And neither Addie nor Lass will escape unscathed.