Board Thread:General Discussion/@comment-11492600-20130929140723/@comment-3146930-20131002012314

Spartan:unknown wrote: They saw that Luke would turn evil and die. but they couldn't intervene.

The Fates most likely knew some of the key events leading to the final confrontaion between Luke and Percy. They knew Luke would eventually turn evil and side with Kronos, but 'choice' is a powerful thing. Looking at the Great Prophecy, Percy had two choices:
 * 1) To try and attack Luke, causing Kronos/Luke to defend themselves, leading to Kronos burning away Luke's body and rising fully.
 * 2) Percy giving Luke the knife and allowing him to kill himself.

Either way Luke dies, which the Fates knew. However they may not have seen how he dies.