From a scroll describing the realm of Aesir, God of War:
In the First Age of Humanity, the city of Caanae prospered under the dutiful teachings of the cults of Peace and Light. Kalika Aisling, a descendant of the progenitors of both cults, knew that her destiny was not to follow the footsteps of her ancestors. A terrible tempest swept through Caanae on the eve before Kalika's rebirth as a Prophetess of Hope or Peace.
While Kalika kept her vigil that night, voices spoke to her from the storm, speaking of conflict, bloodshed, and power. When dawn came, Kalika's Path of Fate led her through the Path of Peace, past the Path of Light, and brought her face to face with the God of War. Taking her hand, Aesir led her down the Path of War, raising her up to be His first Prophetess.
Aesir provided the impetus behind the founding of Stavenn, frequently reaching out His hand to direct the course of War within Aetherius. He revels in conflict and strife, but understands the importance of reason behind action. True war does not equate to common thuggery.
The God of War wears a constant thundercloud around Him, hiding His appearance when He chooses to make Himself visible to mortals. Very few mortals have been given the distinct honour to look upon His true form.
History
Despite it being the sort of thing one would imagine He would participate in, Aesir was relatively quiet during the war between the Gods of Imperian and the Demon Gods. He participated in the final battle of the conflict, weakening Azoab before being cruelly torn apart by the jaws of the Demon Lord.