Perhaps I have this all wrong, and maybe you'll tell me I have it mixed up.
But I think true friendship needs a pinch of selfishness.
Break the rules a little to ask and hope for something you want in the other...even if you know it might be hard for the other to answer you.
To not be afraid to ask, coz you hope for a return.
But then again, you have to...
Give slack a little and give yourself out to answer the other.
To not be afraid to be asked, because if you have to... you can say no.
So I guess, if we all add a pinch of selfishness to friendship, it cancels out to make it all ok.