Quirinus

Quirinus was a Roman God of Warfare, he was included in the earliest precursor of the Capitoline Triad, along with Mars (then an agriculture god) and Jupiter.

Minerva states that back in the mythical age, Quirinus's offensive power was second only to the King of the Gods himself: Jupiter, he wants to participate in the decision making and seeks to destroy Mars just for usurping him as a War God even though he doesn't wish the Title back.

Quirinus is actually the Immortal form of the Demigod, Romulus, this makes Mars technically his father. When he was reborn as an Immortal, he lost all memories of his mortal life, and gained a new name.

Trivia

 * It is implied that the name Quirinus be derived from the Sabine word quiris "spear".