Opinions on 'Fan' relationship model in RESTful app

I'm working on an app in which users can become a 'fan' of another user. I'm trying to determine if and how this is similar to a 'friendship' model, like the one seen in the has_many_friends plugin, but I haven't got my head round the differences yet, so I'm looking for advice. I'm coming to the conclusion that 'fans' are different to 'friends' because a user can have a fan without themselves being a fan of the fan, whereas a friendship model requires both users to be friends with one another when the friendship is created.

Use case;

A User1 clicks a button on User2's profile page to become a 'fan' of User2. User2 will, depending on their email notification settings (yes/no), be notified that they have a new fan.

That's pretty much it, but I'm also considering an option which enables users to first approve of other users becoming a fan. This would be specified in a profile setting. I presume this function will necessitate adding a 'status' to the fan table and adding 'requested' statuses etc.

How would you set up this up in a RESTful app?