Sorry. Coming from LJ I'm used to using their terminology, which is friending (means you can follow them and they can see your posts; if they friend you back, you can see their posts).

Subscribing on DW means you can see them on your reading list (but not locked posts unless they also grant you access), and granting access means they can see your locked posts. If they also subscribe to you and grant you access it's a total two way street. Some people have full circles (LJ friends list aka f-list) and don't always subscribe back, though they'll give you access if their fic is locked, for example.

I hope that wasn't too confusing. o_O