“Who of you doesn't recognise this sword? I must warn you the Mystletainn craves blood! So who wants to be its first victim?”
—Ares in Genealogy of the Holy War
When Seliph's liberation army passes through the border, Ares leaves to fight with Jabarro. Jabarro confesses that Bramsel, the lord of Darna, has imprisoned Leen and urges him to forget about her. Ares, enraged, turns against Jabarro, despite the latter having raised him after Grahnye's death. In order to save Leen, Ares decided to join Seliph's army, albeit reluctantly, as he believes that his father was betrayed by Sigurd. He will later learn of the truth behind his father's death upon meeting Nanna, who explains that Sigurd did not betray Eldigan, and that the two were always friends despite how things eventually turned out.
Ares is one of the most overpowered characters in the game, which is a rather fitting role for the son of Eldigan. He starts out with the Mystletainn, a formidable weapon that bestows its user with the skill Critical, essentially allowing Ares to just about wreck havoc upon the battlefield. The Mystletainn also gives him a huge +20 boost to Skill, and a +10 boost to Resistance, which further enhances his usefulness as a unit. His Resistance growths are strangely high for a non-magic user, which are, however, highly desired in light of the skirmishes undertaken in Generation 2.