Hades contains one of gaming’s most complete love stories embedded in its roguelite loop: Achilles — the war trainer in Zagreus’s house — and Patroclus — a shade in Elysium — are separated by Achilles’s honour code. Achilles cannot enter Elysium while his contract with the House of Hades remains active. They have not spoken since the Trojan War.
The questline requires talking to both characters across multiple escape attempts, finding a specific letter, and delivering it across the living-dead divide. The reunion itself is not a cutscene; it is a conversation available at Patroclus’s shade location that Zagreus can witness or not.
Supergiant built the reunion to be unhurried. Players who arrived at the right moment and stayed through the full conversation received one of the few instances in the game where two characters are simply glad to see each other — no dramatic stakes, no new information, just the fact of reunion.
The Greek source material — the most famous male relationship in classical literature — is treated by Supergiant with care and without annotation. Achilles and Patroclus are what they are in the Iliad. The game does not underline it.

On my first run and now I have to go back and look for this. Worth the detour.
Found this by accident on my third run. Came here to understand what I was looking at. Great write-up.