How can I talk about the motif of the ransom at a symbolic level?
Ransom:
the redemption of a prisoner, slave, or kidnapped person, of captured goods, etc., for a price.
the sum or price paid or demanded.
a means of deliverance or rescue from punishment for sin, especially the payment of a redemptive fine.
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One could also say that the ransom or the price to have one's stories to last after their death is their untimely death. - Priam and Achilles
Also, Achilles was ransomed (rescued from his grief) because he was able to let go of his anger and rage for the death of his mate Patroclus. Priam is also liberated because for the first time he is allowed to feel like a normal human, and just like any father.
You could also say that for one to learn about life, one could turn to literature and for example, 'Ransom' is a text where you can learn something from. People can also be delivered from their ignorance through literature and having stories told and retold to fit modern readers. So, the ransom, in a sense, for people who want to learn about things--about life, humanity etc is to read the text 'Ransom' and to come out understanding that Malouf does have a point and that as authors there is always something to give to their readers.
I'm tired right now so I can't really give you more details but I hope that has helped you. My fingers are so cold too.