You add them = you're their fan.
They add you back = you're friends.
If you both decide to add each other to each others circles then you become friends. In your case anyone over the age of 18 can't be the first to initiate the process. If you want to friend anyone over 18 on here you have to add them to your circle first. It's to keep the creepers at bay.
It's interesting they mix the two together. Wish they would make fan and add to circle separate. No complaints on people I fan adding me back to make them a friend though! :)
Yeah. It's EP's way of friending someone.
ANd it gets weirder. Until THEY ADD you, you are labeled as a FAN of theirs.