Demon Defeat, Part One by M.J. Haag

Only the strong survive.

It’s been months since the earth opened up and unleashed hell on us. Months scouring the decimated Midwest in search of a way to stop the spreading plague and save what’s left humanity.
Instead, I discover something far more vital.
Whatever hell unleashed is following us. He has the body of a gladiator and the cunning mind of a general. He also has the power to stop the plague at its source. And all he wants in return is me–willing or not.
But, in order to save what remains of the world, he’ll need to risk the one thing he wants most. Me.