Long before the rise of Tulak Hord, Dûma was an akolythe in the sith academy. But he lacked the ambition and cunning the others had and thus was deemed utterly useless for becoming a Sith and, going accord with this prediction he quickly was betrayed and left for dead in one of the caves around the Academy... where he surprisingly survived due to the intervention of an hermit and, taking an example of his style of life he turned his back to common sith socoiety and chose a life far off this academy deemed him unworthy and 'weak'.
Life in the wilderness of Korriban steeled Dûma and by the time he entered the service of Tulak Hord he was as dangerous with his Hands as others were with a sword or a gun so naturally he quickly was initiated into the circle of Tulaks most elite warriors, the Sixfingered Hand as the most proficient in Hand to hand combat and likely also the strongest among Tulak Hords warriors.

It is unknown why Dûma reentered the Sith society and entered the service of Tulak hord. Maybe he was personally convinced by the Dark lord? Maybe he lost a duel and so was cursed to a lifetime of servitude? Only the Massassi Sith knows and he does not talk.
Completely lacking of any cunning or ambition he might aswell be deemed the perfect soldier, or weapon he will attempt to brute force his way through any obstacle between him and his target.

Duty 10
Obligation 10 Betrayal (No xp/money for that, only for narrative reasons)

Dûma is rather small for an massassi at 2 metres and without the statue of an giant. But the hardships he had to endure made him strong nonetheless
His skin is off a glowing red just as his eyes glow in yellow, a clear sign of his strength in the dark side of the force.