Under Her Skin by Aria Cole

Sienna Taylor walked into Aspen Ink looking for a temporary escape. Instead, she found River Madden, the gorgeously talented and impossibly moody owner of the shop. One look in her big, dark eyes makes him desperate to possess her, his need to mark her luscious skin a primal distraction.
One touch of his needle sends electricity rocketing between them, and by the time he’s finished leaving his brand on her, he’s doing the unthinkable and offering her a job, and possibly losing his sense of sanity.

Finding forever is the last thing on River’s mind, but one taste of her sweet innocence has him consumed with claiming her.
She’s too innocent, too sweet, too untouchable, and far too good for him. But she has a darkness that claws at her, a crack fracturing her heart that only makes him crave her more.