What does it mean, when someone becomes a ファン of me?

It's fanpop's equivalent of a friend request.

depends on the user
some just obsessed of getting もっと見る number of fans
some wants to be friends
some add after seeing that あなた both have lots in common
some just add あなた and never get back lol

Nothing. Everything will seem meaningless when we are in control! All your mortal ファン will be irrelevant compared to the イルカ Council and their great rule! I'm kidding. It means potato.