When you turn 16 you go somewhere to get a special necklace and a tiny piece of paper that says if you're an omega, beta or alpha. The necklace determines your soulmate and you go onto this journey to find your true love with the help of a necklace. That's what happened with Louis and Harry. Two best friends since childhood and always having a special bond with each other. When they both find out that they have the same necklace and are meant to be together forever they react in different ways. Harry is decently okay with it while Louis is most definitely not.