The suitors have been trying to court Odysseus's wife and have eaten his livestock and taken advantage of his property. Though they are ready to pay...

The
question of why Odysseus slaughters the suitors is an engaging question and one usually taken
for granted. Throughout the Odyssey, one big theme that modern readers have
difficulty engaging with is the guest law, or guest-friendship (xenia, in
Greek). In some ways, the Odyssey is really a story about guests and hosts,
and what is the proper conduct between them. Antinous and the rest of the suitors demonstrate
bad guest conduct early and often. As early as book 2, Telemachus holds an official assembly and
asks the suitors to leave, to which Antinous calls his would-be son-in-law an insolent
braggart. Even when the best prophet in Ithaca warns them that Odysseus will return soon,
Eurymachus, another suitor, threatens him:

Go home, old
man, and prophesy to your own children, or it may be worse for them ... We shall go back and
continue to eat up Telemachus estate without paying him.

is making the point that this are not how guestssuitors or otherwiseare supposed to act. They
have overstayed their welcome, and they know it. They are insolent, rude to Telemachus and his
mother, and display . It is difficult to make the argument the suitors deserved to die, because
xenia was a huge cultural concept in Ancient Greece and is not so much of
one today. It is akin to trying to explain seppuku among the samurai class
or bullfighting in modern-day Spain. Some concepts that are steeped in culture and tradition in
one place are difficult to explain in others.

In case there was any room for
doubt that the suitors needed to die, Homer gives one more instance of Antinous (who is the
worst of the suitors, but also a sort of synecdoche for all of them) acting unruly. When
Odysseus returns home and walks into his palace disguised as a beggar, Antinous does not greet
him with propriety but slings insults at him:

Have we not
vagabonds enough without him, nuisances of beggars enough to mar our feast?

He goes on to hurl a footstool at him, which is entirely
inappropriate.

There are other explanations for why Odysseus kills the
suitors that can be argued outside of xenia. For one, Athena seemed to be
directing Odysseus toward it. Perhaps at that point in the story, the weary Odysseus has been
consumed by violence. He is also the king of Ithaca, and having an entire generation of young
men who lived in his palace, ate his food, disrespected the prince, and made advances on the
queen undermines his authority and does not bode well for the future of the kingdom.

It should be noted, along with the suitors, he also hangs twelve maids who were
assaulted by the suitors. If you would like further reading on them, The
Penelopiad is a fantastic short novel by Margaret Atwood.