Achilles is in your alleyway : What we learn about him in Ransom

Achilles is a cruel, narcissistic bastard - that's obvious to everyone who's read The Iliad and it's equally obvious to readers of David Malouf's retelling of the tale, "Ransom." First 50 or so pages focus on "the wrath of Achilles," and give quite a gruesome account of his lashing Hector's body to the axle tree (a word I'd only seen in Eliot till now) and dragging him around the walls of Troy. In a touch that I don't think is in the original, Hector's body seems to recover miraculously each night, so Achilles drags him again and again - Sisyphean. Not sure why Malouf adds this supernatural element. He tells us (doesn't show) that Achilles sacrificed many on the "barrow" (pile or mound at a funeral site - who knew?), including several horses and Trojan prisoners. Violating the body is one thing - sure to incite the wrath of Priam and the Trojan leaders. But why kill horses and why mistreat prisoners of war? Those are violations of all convention, barbarous behavior - and any talk about well, Greeks used to do lots of sacrifices etc. is just wrong - this isn't sacrifice, it's slaughter. So why does Achilles do this stuff? Is he just insane? Enraged? Here's an area where Malouf could give some enlightenment, because Homer didn't - is it homoerotic? (not a hint of that from Malouf), or just a powerful sibling friendship (that's what he implies, but doesn't develop), or weird injury to his warrior pride? Book so far very well writen, if a little too aware of its own vocabulary and burnished style - but I'm waiting to see what insights Malouf offers - or is it just a retelling of the familiar?