Drev Hassin existed as a male Askajian Padawan. He was a servant of both the Jedi Order and the Galactic Republic during the era of the Great Hyperspace War.
Being a Force-sensitive Askajian, Drev Hassin possessed a strong understanding of his people's traditions, despite his departure from his home planet to undergo training in the Force with the Jedi Order. He was hand-picked by Jedi Master Relin Druur for specialized instruction, becoming Druur's Padawan and dedicating himself to service throughout the Great Hyperspace War. In the year 5000 BBY, he joined Druur on a quest to locate Druur's former Padawan, Saes Rrogon, who had succumbed to the dark side of the Force. They discovered him in league with the Sith Empire and relayed this information back to Coruscant, before pursuing him to the Phaegon system. It was there that Rrogon, in command of the Sith dreadnaught known as the Harbinger, engaged in mining operations for the valuable Lignan ore located on a moon orbiting Phaegon III. Hassin and Druur, piloting an Infiltrator starfighter, launched a surprise ambush against the Sith. Druur boarded the Harbinger with the intention of disabling the ship's hyperdrive to prevent the delivery of its precious ore to Sith Lord Naga Sadow, while Hassin faced an onslaught of Blade-class starfighters launched from the Harbinger and its companion vessel, the Omen.
Hassin successfully fended off the attacking fighters for a period while Druur carried out his sabotage of the Harbinger's hyperdrive and engaged Rrogon in a duel. However, Hassin's endurance reached its limit, leading him to make the decision to crash the Infiltrator directly into the bridge of the Harbinger. The dreadnaught was unable to evade his suicidal maneuver, and Hassin's ultimate sacrifice resulted in the Harbinger colliding with the Omen just as the ships were attempting to jump to hyperspace. Consequently, the Omen crash-landed on the isolated world of Kesh, leaving its survivors marooned there for millennia. Meanwhile, the Harbinger was pulled into an erratic hyperlane that propelled it 5,000 years into the future, arriving in 41 ABY. There, Druur, deeply affected by Hassin's demise, fell to the dark side before confronting Rrogon once more in a duel that ultimately resulted in the deaths of both combatants and the final destruction of the Harbinger.