Philoctetes

Philoctetes' wound not only would not heal, but grew so odorous and painful that his companions could stand neither his agonised cries nor the stench of the sore. Agamemnon ordered that he be marooned on a deserted coast of the island of Lemnos … In the last year of the war [a seer] foretold that Troy would fall when Achilles' son and Philoctetes were both brought to fight with the Greeks.
— Edward Tripp
Caused by the blood
of the unkillable Hydra,
Philoctetes' wound refuses
to heal, or let him die.
He festers in isolation
on Lemnos—a warrior living
with perpetual defeat by
an opponent who will not
drive the sword home.
He fights lassitude,
despair, virulent anger,
coming at last to understand
his enemy, the poison,
to follow its changing strategies
and moods till it becomes
almost a companion.
When those who left him
come to take him back
to the war they cannot win
without him,
he finds a reluctance
to leave that place where
he had begun to know
the conundrum, pain —
keeping him alive
against so many odds.