Dwalimar hailed from Halruaa. In one of the adventures he undertook for the Netyarch, he was sent to acquire the Astrolabe of Nimbral for his nation. While the mission was a success, his human companion was killed, and he only managed to save his dwarven friend Minder by placing her soul in a golem.
Years later, the Netyarch Zalathorm Kirkson gave Omen the mission of finding and destroying dangerously powerful artifacts using the Astrolabe. On the journey, he gathered a set of companions, including Minder the golem, Foxilon Cardluck the halfling, the humans Priam Agrivar from the north and Ishi Barasume from the east and the elf Vartan Hai Sylvar.
At the start of the Time of Troubles, Vartan was chosen as a vessel for his god, who immediately commandeered the Realms Master, in order to attack Helm and return to the heavens. The crew managed to defeat him and cast him into the Demiplane of Fear, where Dwalimar kept all his most dangerous artifacts, but not before it was too late to change course, and the ship was destroyed by Helm.
The loss of the ship took a heavy toll on Dwalimar's mental state, not helped by the destruction of Minder and changing of the rules of magic following the Time of Troubles and Mystra's ascension to godhood. While the crew were stuck in a desert, Dwalimar spent all of his time pouring over his spell book trying to relearn everything, often remarking on changes (particularly that magic missile was less effective).
Omen had a hot temper and a huge ego but was a fatherly figure for his crew. Omen used to be pompous and stern to impress people and charming when he wanted something. His disease could leave him very moody. However, a difficult task would galvanize Omen and he would forget his condition for a time. Omen first and foremost thought about protecting people from those that abused their power.