Nightside 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. She 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.
Nightside was later amongst those few Imperial Guard members who opposed the treacherous Shi'ar High Council member Lord Samédàr who was aiding an attempted coup of the Shi'ar throne by Deathbird. Even after many of the Guard chose to side with Samédàr, Nightside remained steadfast in her loyalty to then-Empress Lilandra.
Later, after the formerly-exiled Deathbird had usurped the Shi'ar throne, Nightside 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.
During the war between the Shi'ar and Kree Empires, Nightside was part of a small team of Guardsmen who were charged with preventing the member of the Earth team of super-powered beings known as the Avengers named Quasar from retrieving the legendary Nega-Bands of the Kree warrior Captain Mar-vell, which had been stolen.
When the Empress Lilandra, having regained her throne, 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 Nightside, to protect Earth. While on Earth, 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.
Subsequently, Nightside 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.