The Immortal Who Loved Me (Argeneau #21) by Lynsay Sands

A few hours ago, Sherry Carne would have sworn that vampires didn’t exist. That’s before rogue immortals rampage through her store, leaving bloody chaos (literally) in their wake. The kicker comes when Sherry learns that one of the vamps on the bad guys’ trail may be her life mate. Her head says it’s impossible. The rest of her takes one look at Basileios Argeneau and has much more interesting ideas.

Whatever Basil expected in a life mate, funny, outspoken Sherry isn’t it. But mind-blowing chemistry and instinct don’t lie. They tell him something else, too—that Sherry’s connection to the immortal world goes deeper than she knows. And that she’s in the kind of danger only Basil can save her from—if she’ll just trust him, now and forever . . .