Twitter-like follow button
It turns out I was going about this the wrong way.

To create a Twitter-like follow button the best thing to use is the module Flag.

Create a Flag called "Follow Me" (follow_me)

Create a Content-pane View which has:


Sort Criteria: Content: Type (=MyContent)
Context Filters: Content: Nid
Relationships: Flags: follow_chapter (by current user)


This content pane then can be used with Panels.

You can then create another view with the relationship with Flags: follow_me to get a list of content followed by the user.