Daddy’s Little Librarian by Maren Smith

An ex-cop sent to prison for something he didn’t do, Kurt Doyle knows from experience that nothing good ever happens on a Monday. So when his Grams hooks him up with a friend in need of a bodyguard, he knows better than to get involved… until the Little in Scotti Moore provokes the dominant Daddy in him. She’s small, she’s sweet, she’s innocent. She’s almost more trouble than she’s worth, and she’s a librarian, for crying out loud. But she needs his protection, and even if she is everything he wants, he knows the last thing she needs is a man who brings more trouble.

Originally published as The Bodyguard. However this version has been completely re-written and expanded. It is almost nothing like the original.