The Triad

The Triad was an alliance of three good-aligned deities: Tyr the Maimed God, god of justice; Ilmater the Broken God, god of suffering and compassion; and Torm the True, god of duty. After the Spellplague of 1385 DR, the dragon god of justice, Bahamut, became a member of the Triad, temporarily replacing Tyr until his return after the Second Sundering.

They resided on a celestial plane called the House of the Triad, and, after the Spellplague, they resided in the astral dominion of Celestia.

History
In -247 DR, Tyr first appears in Toril, in the lands that would be later known as Turmish, and led a force of 200 archons to purge the former lands Jhaamdath, that had fallen into anarchy and chaos. This campaign was called Procession of Justice. The Procession caught the attention of Ilmater, at the time an obscure deity who had similar ideals to those of Tyr, and in -243 DR, Ilmater and Tyr became allies. At some point before -238 DR, Torm, at the time a demigod, joined Tyr's forces, almost decimated at that point, as his war leader. Eventually, the alliance of the three deities became known as the Triad, who remained allies even after the Procession was over in -238 DR.

During the Fiend Wars of Impiltur, in 729 DR, an army dedicated to the Triad started the Triad Crusade. This led to the foundation of the Triadic knights, an order of paladins dedicated to the Triad. Several other crusades were launched over the course of history in their name.

During the Time of Troubles of 1358 DR, Torm was killed while battling against Bane, who also died in the battle. Because of his loyalty to his portfolio, Lord Ao resurrected Torm shortly after the end of the Time of Troubles and Tyr raised him to the status of lesser deity.

In 1384 DR, the dark god Cyric manipulated Tyr to battle Helm, god of guardians, over a misunderstanding. Tyr won, and Helm died. This divided the Triad, as Ilmater chose the leave their shared plane, the House of the Triad, to live with the goddess Sune in Brightwater. Crushed by grief and shame, Tyr abdicated his godhood and granted Torm all his deific power. Tyr counseled all of his followers to offer their allegiance to Torm.

In 1385 DR, after the Spellplague had wreaked havoc in the planes, a group of demons led by the balor lord Axithar invaded the House of the Triad, and when Tyr and Torm send calls for help, the dragon god Bahamut answered by sending his legions to aid in destroying the demons. However, Tyr died while defending the celestial planes during the ensuing battle.

Afterwards, Torm became the chief deity of the Triad and promoted Bahamut to the same position he once occupied while serving Tyr and Ilmater joined his fellow god once again. The three gods moved to the plane of Celestia and re-purposed the role of the Triad in the Realms. In this "new" Triad, Bahamut took the role of the god of justice in place of Tyr, while Ilmater became the god of mercy, and Torm the god of law, acting as a point of balance between the other two gods.

After the Second Sundering in the late years of the 1480s DR, Tyr returned to life and resumed his role in the Triad as the god of justice.