The Song of Achilles question

Patroclus knew Achilles better than anyone else, better even than his father and so did Achilles with him.
As far as Achilles was son of a goddes, it doesn't mean he wasn't son of a man, too.
This is what I particularly like about The Song Of Achilles: Achilles is presented as someone to fear, whose training must not be seen, who is boundto kill Hector and then burn Troy down, whereas he's just a man, and only Thetis, who tries to solve his mortality, and Patroclus, who loves him for what he actually is, know.
Homer, Diomedes and Odysseus don't know Achilles as much as Patroclus does. They just meet him in the battle, whilst Patroclus meets him in their tent, while eating, singing and making jokes together. He meets him in their intimity, too. Patroclus knows Achilles far better than anyone else; Achilles seems more human when Patroclus is describing him because that is exactly how Patroclus has always seen him.

There is also a sense of idolisation which distorts Patroclus' presentation of Achilles- though, seeing as the two were lovers, this idolisation would be two-sided. Patroclus admires Achilles with the telltale awe of any mortal-demigod dynamic, but also with a kind of humanity that would be unattainable to any other mortal, because Patroclus is truly in love with Achilles.