He was born in 1967 and became a member of the Estovakian Air Force sometime in his life. Gustav has a daughter named Irena who was an Estovakian Air Force pilot and stays in the front lines despite her father's orders to retreat from the area.
When the Estovakian Civil War broke out, he assumed his position as the Supreme Commander of the Eastern Faction, and with the power of the P-1112 Aigaion, he and his forces emerged the victor of the Civil War. He formed a committee of military officials called the Generals to restore order to the Estovakian government as a dictatorship. Then, he assumed his position as the Central Forces Precinct Commander and Expeditionary Forces General before the Estovakians used lightning strike tactics to invade Gracemeria, successfully taking control of the capital on August 30, 2015. Despite this, the Emmerians began to retaliate by destroying the Estovakian Aerial Fleet and killing his daughter Irena. Later, he fled Emmeria prior to the liberation of Gracemeria and went to Sonne Island to use the anti-asteroid railgun Chandelier as a last resort to destroy the Emmerian capital. Upon hearing this, Talisman, Shamrock and the rest of the Emmerian pilots began a final assault on the Estovakian territory in an attempt to destroy the Chandelier on April 1, 2016. With information sent by Melissa Herman and her daughter Matilda through the radio station in Gracemeria, Talisman succeeded in destroying the cooling units, with Shamrock presumably sacrificing himself to find the location of the backup cooling unit. After Talisman succeeded in destroying the cooling unit, the Chandelier's core was revealed inside the barrel, preparing to fire a final cruise missile. As Dvornik attempted to escape the Chandelier in his F-4E Phantom II, Talisman attacked the Chandelier's runway, shooting down and killing Dvornik as well as his three escorts before flying into the core of the Chandelier and destroying it, finally ending the war.