Followers
Followers represent a social relationship between two Profiles. Unlike Friends, two Profiles make a follower/followee relationship and the relationship is much more loosely defined. Followers rely only on Profiles, and therefore all information in the Follower/Followee relationship is public information. The APIs dealing with followers return Profile instances.
Followers are meant to allow for casual relationships among users of a particular application. Because they operate strictly on Profiles and public information, there is no need for modeling Following as a mutual relationship. Either user may follow or unfollow others as they see fit.