Banshee

Finding the girl of your dreams in your rivals gang's garage, and knowing it will start a war if you claim her.
Well, you only live once.

Rival's gang's President's little sister
Shifter romance aficionado
Sarcastic
Sassy

As soon as Banshee, the Enforcer of the Reaper's Rebels saw Finley he knew she was his. Even if she was the little sister of the rival's gang's President. Now, Banshee has to convince Finley's brother she belongs with him or there will be a war between the gangs, but either way, Banshee is keeping her.

Instalove motorcycle novella with a sassy female that loves shifter books, a hulk of a biker who fits all the shifter qualiications except he doesn't shift into an animal, well except in bed.