Θάνατος, Φως και Λάθη (Light, death and mistakes.)

WRITTEN IN ENGLISH!

Two young demigods are cornered by a hell hound, what happens when the older one sacrifices themselves for the young boy. They dedicated their life to Apollo and have a fear of females, when Apollo tries to take her to the underworld he notices something is wrong and goes to find Thanatos, the god of death. Exactly what went wrong?