[Mars] is generally interpreted as a symbol of masculinity, male directedness, self-assertion, aggression and competitive instinct. All of this is no doubt true, and the typical Arien personality, male or female, usually possesses some share of these direct and forceful attributes, whether on a physical, emotional or intellectual plane. But this describes the Arien side of Mars. He has another face, his 'night house' as medieval astrology was wont to call it, and this is the Scorpionic side of the planet; and he has kinship with Pluto in many ways. Walter F. Otto in The Homeric Gods gives a fine if unsettling descriptive passage on the war god Ares, whose Roman name is Mars.

"Ares is sketched as a bloodthirsty, raging demon, whose confidence in victory is nothing more than braggadocio compared with the rational power of an Athene. 'Mad' and 'insane' the gods call him; he does not know 'what is right', and turns, with no character, 'now to one and now to another'. To Zeus himself 'no Olympian god is so hated' as he, for 'he thinks only of strife and wars and battles' . . . The figure of Ares derives from the antiquated earth-religion, where his savagery had its proper place among other pitiless forces. He is the spirit of imprecation, vengeance, blood-guilt. As the daimon of bloody slaughter, he still possesses fearful stature for Homer. His element is manslaughter; he is called 'the destroyer', the 'slayer of men'."

. . . According to Hesiod's cosmogony of the gods, Ares is the parthenogenous son of Hera the Great Goddess. The birth of Ares occurs because Hera is infuriated with Zeus; he has had the audacity to generate the goddess Athene from his head without a female consort, and Hera must one-up him. To couch this in psychological jargon, Athene is the anima of Zeus, the feminine wisdom of the male; and Ares is a rather negative form of the animus of Hera, the fighting spirit of the female. That Ares is a mother's son immediately relates him to Hades, who is a mother's phallus. Zeus, in Homer's Iliad, feels that Ares' proper place is among the Titans banished in the deepest depths of Tartaros. This war god has no dignity and no honour; he is of enormous size (700 feet tall) and utterly treacherous. In short, Ares is an image of Hera's outrage.
 
Liz Green, "The Astrological Pluto"