According to Hesiod, Orthrus was the father of the Sphinx and the Nemean Lion, though whom Hesiod meant as the mother, whether it is Orthrus’ own mother Echidna, the Chimera, or Ceto, is unclear. Yes, it can get a bit messy and incestuous, particularly when we are talking of snake-bodied monsters.

Orthrus and his master Eurytion were charged with guarding the three-headed, or three-bodied giant Geryon’s herd of red cattle in the “sunset” land of Erytheia (“red one”), an island in the far west of the Mediterranean. Heracles killed Orthrus, and later slew Eurytion and Geryon before taking the red cattle to complete his tenth labor. According to Apollodorus, Heracles killed Orthrus with his club, although in art Orthrus is sometimes depicted pierced by arrows.

That’s the thing about mythology – never let the truth spoil a good story. Remember, they didn’t have Netflix. All they had was myths and bards.