The Unlikeable Demon Hunter by Deborah Wilde

The biggest threat an all-male brotherhood of demon hunters face isn’t any demonic foe. It’s a foul-mouthed, romance-impaired heroine who’s gonna show these boys a thing or two about how to really slay a monster…

When Nava half-drunkenly interrupts her twin brother’s induction ceremony into a secret supernatural society, she doesn’t expect to accidentally torch his life-long dream and steal his destiny.
Horrified she’s now expected to take his place, Nava is faced with something she never wanted: a purpose.
The society isn’t cool with a woman in their ranks and teams her with a surly but smoking hot ex-rock star to keep her in line. A hook-up with him is as dangerous as the vengeful demon out for blood–her brother’s.
And Nava’s the only one who can save him.
Odds of survival: meh.
Odds of a good time before she bites it: much better.