This is by H28 on onedirectionfanfiction.com it's wonderful and I hope you like it as much as me. Recommended for 17+

Working for a world-leading mafia, Harry knows how to kill, how to hunt his victims, and how to avoid any company of any kind. He's used to a lonely, quiet, and harsh environment. He is the best at what he does. And everything he does becomes problematic when he's assigned to protect the boss's daughter from world-known killers. Catalina tries to understand him, eventually failing because instead she falls for a man so willing to resist her. [Contains Mature Content]

Tessa Young is an 18 year old college student with a simple life, excellent grades, and a sweet boyfriend. She always has things planned out ahead of time, until she meets a rude boy named Hardin, with too many tattoos and piercings who shatters her plans.

This is the sequel (continuation) of After. Hardin and Tessa's relationship will be tested in ways she never expected, but he knew of all along.

The passionate story of Tessa and Hardin continues as family secrets, deep betrayals, and career opportunities threaten to tear them apart.