Discord is an ancient spirit-being created by Lenorissa during the creation era of Lenor's history. Originially, he was a being of order and tasks, and he looked very different from today. He was tasked with maintaining balance and order in Lenor and Equestria after its creation. He did, until Chaos entered Existence and encroached on Discord. The dark powers of Chaos warped his body and his mind, turning him into the current Discord.
Under command of the Chaotic deity Yorgoth, Discord and Grandmaster Eliphas, the corrupted Alicorn General-Supreme, led the Hundred Years War offensive against the Loyalist Alicorns under command of Pelenal the Vigilant. After the war's conclusion, when Chaos' minions were defeated, Discord fled and began wandering Lenor to spread his madness, chaos, and general mischief everywhere he went. He is an enemy of Princess Celestia, whom he believes is too "tense". Though Discord is one of Chaos' only surviving agents, he does not seek world domination (all the time). He is generally harmless, posing no serious threat to Equestria (right now). But still, he is a presence that Celestia would prefer contained lest he choose to step up his antics.
Discord has a generally neutral affilation in worldy conflicts, sometimes helping evil and other times good. He has even helped Blue team on more than one occasion. He also helped cause the destruction of the Mythic Dawn, helping to end one of the most destructive wars of Earth's history.