The story we hear comes from Apollodorus, addressing an unnamed companion. He tells a story he once told to Glaucon and which he was told by Aristodemus. Glaucon had also heard a version of the story. What is the purpose of all these complex framing devices?
Two answers to this question readily present themselves. One is that these framing devices serve to show the great level of general interest in the symposium. Years after the fact, people are still talking about it and wanting to hear about it. This prepares us for an event of great importance. The other is to distance the narration from the truth of the actual event. Plato wants to make clear that he is inventing most of the story, and not directly reporting factual events. This distancing from the truth also helps to emphasize a central theme, that the truth is something that we must struggle toward.
What is the distinction between lover and loved one, and how does this distinction play itself out in the different speeches?
Sexual relationships in ancient Athens were generally viewed asymmetrically. The lover is the active partner in the relationship and the loved one is the passive partner. In male-female relationships, the man is always the lover and the woman the loved one. In male-male relationships, the lover is usually the older man who pursues the loved one, a younger, beautiful man. The lover normally receives more sexual gratification, and in exchange rewards the loved one with gifts, money, prestige, and wisdom. Many of the speakers (Phaedrus, Pausanias, Agathon, and Socrates most notably) present versions of this relationship as the ideal of love. Agathon presents love from the perspective of the loved one, which is significant as he is the passive partner in his relationship with Pausanias. Socrates presents love from the perspective of the lover, which is significant, as he is an older man who spends a great deal of time associating with, and sharing wisdom with, handsome youths. Interestingly, we find the lover/loved one dynamic largely absent in Aristophanes.
Socrates asserts, against Agathon, that Love is a relational property. What does this mean, and what philosophical significance does it bear?
Love is a relational property because Love does not have any properties of its own. Rather, it connects someone who desires something with the thing they desire. Thus, Love is not wise nor rich nor beautiful nor any of the other things we might ascribe to an object of desire. Rather, Love is that desire which finds itself in the absence of all these praiseworthy qualities. Presenting Love as a relation clarifies its position and identifies the flaws in the earlier speeches given. But in treating this relation as a thing with a nature and properties of its own, Plato is inching toward philosophically dangerous ground.