The Song of Achilles by Madeline Miller

Greece in the age of heroes. Patroclus, an awkward young prince, has been exiled to the court of King Peleus and his perfect son Achilles.
 
Despite their differences, Achilles befriends the shamed prince, and as they grow into young men skilled in the arts of war and medicine, their bond blossoms into something deeper - despite the displeasure of Achilles's mother Thetis, a cruel sea goddess.
 
But when word comes that Helen of Sparta has been kidnapped, Achilles must go to war in distant Troy and fulfill his destiny.
 
Torn between love and fear for his friend, Patroclus goes with him, little knowing that the years that follow will test everything they hold dear.
 
Bloomsbury Modern Classics edition. 
 
-----
 
Winner of the Orange Prize for Fiction
 
'Page-turning ... Nothing strikes a false note in her intricately created world.' - The Guardian 
 
“A captivating retelling of the Iliad and events leading up to it through the point of view of Patroclus: it's a hard book to put down, and any classicist will be enthralled by her characterisation of the goddess Thetis, which carries the true savagery and chill of antiquity.” –  Donna Tartt
 
“At once a scholar's homage to the Iliad and startlingly original work of art by an incredibly talented new novelist ... A book I could not put down.” –  Ann Patchett
 
“Inventive, passionate, uplifting and different ... A truly worthy winner.” –  Joanna Trollope