Thanks Burt and JJJ.
So, logged-in user A visits the profile of user B and, under the “Add Friend” and “Send Message” buttons, there is a “Follow” button.
Pressing this causes:
1. User A’s avatar and name, linking to his profile, to appear in a section of User B’s profile called “Fans” or “Followers”.
2. User B’s avatar and name, linking to his profile, to appear in a section of User A’s profile called “Following”
3. Relationship is upgraded to Friends is user B ever happens to follow user A … OR request A’s friendship.
(4. Possible feature for later implementation, but not a priority – The activities of users you follow appear in a special Twitter-style stream section of your home page).
I am not a coder but, from your discussion, it seems it would be relatively straightforward, but would it put too much load on the server?
I figure it would be roughly the same burden as the Friends feature, but possibly more because people may well end up with more Followers/Fans than Friends i.e. your profile might display 3 of 3 Friends but 5 of 30 Followers/Fans.