For some time, marketing and leadership gurus have been advising professionals to 'tell more stories.' If you're looking to persuade people, they say, stories are more memorable and compelling. (See The Story Factor, among others.) 

According to Seth Godin:

The story has to be integrated into your product. The iPad, for example, wasn't something that people were clamoring for… but the story of it, the magic tablet, the universal book, the ticket to the fashion-geek tribe–there was a line out the door for that. The same way that every year, we see a new music sensation, a new fashion superstar. That's not an accident. That story is just waiting for someone to wear it.

Now we're seeing some thought leaders differentiating between 'stories' and 'narratives.' Unlike stories, narratives are incomplete, allowing people to insert themselves into future outcomes. 

John Hagel says, 

Narratives, at least in the way I will be using them, are stories that do not end – they persist indefinitely.They invite, even demand, action by participants and they reach out to embrace as many participants as possible. They are continuously unfolding, being shaped and filled in by the participants.

Narratives, then are a powerful tool for explaining the value of loyalty. You can project the future you'll have with the customer. Of course, that requires you to be loyal to the customer as well.