Chromeri was simply watching Selene drag the moon across the sky when she overheard a conversation
It was Ares. Trying to convine the army to use the monsters to win the war.
Remembering how her mother was eaten by a monster, Chromeri tried to warn him of the monsters strength
But Ares saw Cromeri as Achilles new lover. For he had lost his and stopped fight to mourn, Causing greek to lose. So tied her up and ran to Archilles tent.
Luckily, Achilles was smart enough to know Chromeri was the messanger of the Sun and Moon god. Saying how Ares will be struck down from both their rage. Ares tried to convine Achilles to take Chromeri, but he kept denying.
So he rushed to Hestia's fire. He wanted to rid of Chromeri. So as Hestia came back with feul, she saw as Ares threw More Chromeri into the fire. Burning her alive.
Both Apollo and Selene were full of grief. So, to always remember the dear messenger, they laid the left behind hair into the sky and the hard tears that turned to diamond across the sky. Catching the suns rays to show color and the stars to lead lost travelors.