On the Lysis of Plato: "All will be your friend if you are wise."
If you are wise, Socrates says, all men will be your friends and kindred because you will be useful and good; but if you are not wise, neither father, mother or kindred or anyone else will be your friend.
This is Socrates' juicy snare for the friendship of Lysis.
Just as for Aristotle the chief good is reason and the sum of all goods happiness, so also for Socrates wisdom is the chief good and love between friends the sum of all goods.
How to account for the paradoxes of friend and enemy Socrates lays out in the Lysis? I think he draws the paradox from the biological and spiritual meanings of friendship. A friend may be useful to practical ends but a bad person ideally speaking. Socrates is being sophistic.
Prudent friendships, as Aristotle reveals, combine usefulness, mutual affection, and pleasure in one anothers' character by doing kind services. And even Aristotle fails to observe the developmental curve: friendships evolve from being mostly useful to being mostly pleasant then to being mostly based in affection. A sound friendship has all three aspects, but at any one time only one aspect is dominant: pleasure, utility, or affection. But all three belong, because we are physical beings as well as spiritual.
(Taking the Aristotle cap off...)
Socrates says "God draws like to like" as friends. True enough. But like in what sense? Clearly what makes friends like one another are questions at the core of human nature. Why are we the way we are? To what extent are we like angels and like animals? In the answers to these questions a view of friendship can arise. But again it is between the animal and the angel that human friendships become possible.
I challenged myself to come up with my own view of friendship. Here it is:
"There is no cause of friendship: all friendships arise in accordance to the field of consciousness as expressions of their own self-nature. Different loves arise from different self-natures. Each kind of friendship is incommensurate to another.
"Broadly speaking, there are three kinds of friendship: horizontal alignment, vertical alignments, and mixed horizontal-vertical alignments. Horizontal alignment friends are mostly based in affection and supportive development of one anothers' full potential; they are heart-based. Vertical alignments are mostly based in utility and issues of control, power, exploitation and predation; they are solar plexus based. Mixed horizontal-vertical alignments are mostly based in pleasure.
On the Map of Consciousness, then, horizontal alignment friendships begin above level of consciousness 500; vertical alignment friendships begin below 199; and between 200 and 499 levels of consciousness of the Hawkins Map of Consciousness are mixed friendships, featuring aspects of both horizontal and vertical alignments."