Compare and contrast Homer's Iliad Book 9 and Book 24 in reference to theme, plot development, and character importance.

In both books, Achilles is unforgiving in his anger, one
of the themes.  He will not relent in either book.  The difference is that in Book 9 he
will not forgive Agamemnon for taking Briseis, even though Agamemnon is willing to give
her back and pay him back handsomely.  This shows us that Achilles is stubborn and too
proud to forgive Agamemnon.

In Book 24 we see a different
side of Achilles.  The book begins with him dragging Hector's body behind his chariot
over and over again.  He wants his revenge, another theme, just like he wanted it
against Agamemnon in Book 9, and once again he is stubborn and won't give up Hector's
body.  The difference then is when Priam appears and begs him for his son back.  We see
a difference in Achilles here.  He gives Priam his son's body.  He gives in because
he is reminded of his own father when talking with Priam.  This is a different Achilles
than the one we saw in Book 9.  Together the men cry over the loss of humanity
altogether, not just for their loved ones.  Together they recognize mortality for what
it is, which is another theme.

Both books appear to be an
end of something big in plot development.  Book 9 sounds like it might be the end of
fighting and war for the Achaians, as they may be heading back home the next morning. 
The last book ends rather abruptly with the funeral for Hector.  The fighting is no
more, and Achilles, the important main character of the epic, has
transformed.