Airman Dunning was one of the military personnel stationed in Icarus Base, under the command of Colonel Everett Young. In 2009, he and 80 others fled the base after an attack against the base, and evacuated to the Ancient ship Destiny. (SGU: "Air, Part 1")
Later in 2009, the Destiny Expedition made a somewhat first contact with an alien race, who start attacking. During the attack, one of the alien fighters latched on to Destiny near Dunning's location. After the aliens drilled through the hull, he witnessed the aliens kidnapping Chloe Armstrong, before they retreated. After a force shield was erected over the hull breach, Dunning reported to Young about Chloe's abduction. (SGU: "Space")
Since the attack, most of the civilians plotted a coup on Destiny. When it came time to act, Nicholas Rush locked down the ship, and separated the military with the civilians. Unfortunately, Dunning and Lieutenant Tamara Johansen were trapped on the civilian side of the ship. He held Lisa Park and two others at gunpoint. He considered shooting them, but was ordered to lower his weapon by T.J. He was held in a makeshift brig until the military personnel took back the ship. (SGU: "Divided")
Later, Destiny dropped out of FTL in an uncharted star system, and would take a month in order to correct its course to account for the system. In the meantime, a team traveled to a nearby seemingly paradise planet. From the start, he had an argument with civilian member Morrison, when Dunning ordered him to dig a latrine. When the argument grabbed Sergeant Ronald Greer's attention, Dunning argued that "somebody's got to do it". Greer sought out a compromise, and ordered Dunning to dig as well. After the month was over, he returned to Destiny, with every over member of the military. (SGU: "Faith")
Dunning in his Hallucinogenic rage
A Tick-like bug was attached to Dunning causing him to hallucinate his fear of snakes being under his skin. In his hallucinogenic rage he cut through the skin on his wrist trying to get the imaginary snake out. He was soon sedated in the Destiny infirmary by T.J where she was able to remove the Tick with the Squiggler Venom. (SGU: "Pain")
Personality
Dunning seems to be attached to those who worked with him on Icarus, he brought a photo with him in his personal belongings of his freinds who died during the attack on Icarus. (SGU: "Subversion")