Flashfire is a member of the Imperial Guard, a multi-ethnic group of super-powered alien beings who act as enforcers of the laws of the Shi'ar Empire. Under his original Guardsman name of Tempest, he was amongst the first of the Imperial Guard encountered by the team of superhuman mutant adventurers known as the X-Men who sought to rescue the Princess-Majestrix Lilandra from her insane brother, then-Majestor D'ken. Following the orders of their emperor, the Guard clashed with the X-Men and were on the verge of winning when the band of interstellar freebooters known as the Starjammers arrived to turn the tide of battle in the X-Men's favor.
Later, after the formerly-exiled Deathbird had usurped the Shi'ar throne from her sister, Lilandra, Tempest was amongst those Imperial Guard members who clashed with the British team of costumed adventurers known as Excalibur and the Starjammers over the fate of the then-bearer of the cosmic Phoenix Force, the alternate future daughter of the X-Man Jean Grey named Rachel Summers.
Much later, the intergalactic teleporter Lila Cheney transported the X-Men to the Shi'ar Empire at the behest of then-Empress Deathbird in time to see Lilandra regain her throne. Not all was as it seemed, however, as in reality a group of Warskrulls, using technology to allow them to duplicate superpowers, had captured and impersonated Xavier, using his telepathy to control Lilandra and the Imperial Guard, including Tempest. After the ruse was discovered by the X-Men and all the Warskrull impostors were exposed, Lilandra settled matters with Deathbird, discovering her sister did not want the throne anymore. During her time as ruling Shi'ar Majestrix, Deathbird had come to despise the responsibilities of maintaining the needs of an Empire as large as the Shi'ar's.
During the war between the Shi'ar and Kree Empires, Tempest was one of a small contingent of Guardsmen that were dispatched by then-Empress Lilandra to retrieve both the famous Nega-Bands of the Kree warrior Captain Mar-vell as well as the powerful device known as the Omni-Wave-Projector. These devices were needed to create the Nega-Bomb - the weapon that ended the war by killing 90% of the Kree population.
When Lilandra learned of the many Earth heroes that had sacrificed their lives to stop the malevolent psionic being named Onslaught, she dispatched eight members of the Imperial Guard, including Tempest, to protect Earth. While on Earth, Tempest adopted the new Guardsman name of Flashfire - which also served to reflect his hot-tempered personality - as the Guard uncovered a plot by a militant Kree faction to simulate a radical political activist group in revenge for Earth's involvement in the Kree/Shi'ar war. In reality, the group created a "nega-reactor", similar to the bomb that was used on the Kree. However, this plot was stopped by the Guard, but not before the reactor was used by the Kree's leader, the Supreme Intelligence, to re-incorporate itself after being presumably killed at the end of the war.
In his time as a member of the Imperial Guard, Flashfire and his fellow Guardsman Oracle had fallen in love and planned to marry. Oracle took the opportunity to retire from active duty with the Guard, and her place was taken by the telepath named Delphos. Subsequently, Flashfire was amongst those Imperial Guard members who defended Lilandra against an assassination attempt by the Kree Ronan the Accuser and his unwilling agents, the royal family of the Earth race known as the Inhumans.