The narrator. Phaedo of Elis was in the cell that day, and the dialogue is structured as his retelling, sometime later, to Echecrates of Phlius — who has heard rumors and wants the full account. This frame matters: we are not watching Socrates die, we are listening to a friend who watched describe what it was like. Phaedo confesses a strange thing to Echecrates — that in the cell he felt pity and pleasure mixed in a way he had never felt before, the unfamiliar compound of grief and the strange happiness of being near a man who was unafraid.
Phaedo — who's who
The cell at sundown — the people who were there.
Phaedo is unusual among Plato's dialogues for the density of human texture around the argument. We are told who is in the room. Six named figures, each registering what is happening in a different key. Together they make the room dense with feeling — and Socrates moves through that density without being swept by it.
The narrators
The man to whom Phaedo tells the story. A philosopher from Phlius who had heard vague reports of Socrates's death but never got a clear account — no one from Athens had passed through. He interrupts twice: once to ask Phaedo to continue more exactly, and once — at the moment when Cebes and Simmias's objections land — to say that he felt the crisis himself, even at this remove. His reaction confirms what Phaedo already said: the arguments did their work on everyone who heard them, then and since.
The interlocutors
On his last day. Calm in a way that makes the friends around him uneasy and that he insists, throughout, is not a pose. He runs four arguments without hurry, takes the objections seriously, teases the weeping Apollodorus, and praises the executioner for the way the man weeps as he brings the cup. Drinks the hemlock without distaste, walks until his legs are heavy, lies down. His last words are about a debt to Asclepius — the healing god — which has been read every way it can be read for two and a half thousand years.
Theban, philosophical, the sharper of the two visiting interlocutors. He raises the worn-cloak objection — that the soul might outlast many bodies the way a weaver outlasts many cloaks, wearing each out in turn, and still die at the last cloak. The objection is the most serious one in the dialogue, because it concedes the soul's longevity while denying its immortality. Socrates's response — that the soul partakes of the Form of Life itself and so cannot admit death — is the dialogue's culminating argument and exists because Cebes pushed hard enough to require it.
The other Theban, also a former student of the Pythagorean Philolaus, also a serious philosopher. He raises the harmony objection — that the soul might be to the body what a tune is to a lyre, an attunement of the parts that vanishes when the instrument is destroyed. The analogy is exact and damaging. Socrates dismantles it carefully — souls can be virtuous or vicious in degrees, harmonies cannot — and the dialogue moves on, but the seriousness of Simmias's challenge is what makes the dismantling matter.
The others in the room
The same Crito who tried to organize the prison escape in the dialogue that bears his name. Here he is older, quieter, doing the practical work of the day. He relays the executioner's request that Socrates not exhaust himself with talk. He receives the final instruction about the cock owed to Asclepius. He closes Socrates's eyes and mouth at the end. Crito throughout the death sequence is the friend whose love expresses itself in unceasing concern about details — and Socrates lets him do it without ever quite agreeing to be looked after.
The friend who cannot stop weeping. Already in tears when the day begins, sobbing openly through the arguments, howling when Socrates drinks the cup — to the point that Socrates has to rebuke him, gently, and remind everyone that this is exactly why he sent the women home. Apollodorus carries the dialogue's grief without filter. He is also the narrator of the Symposium — the same overflowing devotion appears in both. In Phaedo he is the friend whose love refuses to be philosophical about it, and the room is larger for him being there.