I don't think a friendship has much if anything to do with the person you're friends with. You become friends with someone when you become willing to do more for them than you could possibly expect to get back - you develop a stupid, illogical, one-sided relationship with another person.
You give without hoping for anything in return, you take positive things hesitantly and negative things willingly, so on.
Friendship isn't supposed to make sense - on its face, there's no good reason to commit yourself to someone without the prospect of at least getting back as much as you give.
And, in actuality, the sheer senselessness of friendship is what makes it good, what makes it important. Having a friend allows us to become more than who we are, by giving us an outlet for sacrifice.
Doing stupid things that don't adhereto the general rules of a dollar's worth of cash for a dollar's worth of food, an hour's worth of work for an hour's worth of respect, that's sacrifice - it's a violation of the general rules we live our lives by.
Violating these rules reminds us that we're something more than just commodity-exchanging machines. It's noble, it's good, it's the whole damn point of things.
Stone