The Chozo’s security system was partly effective. It kept most of the Metroids in stasis deep within the planet, but some Metroid larvae—their most familiar bulbous form—escaped to the planet’s surface, where a group of researchers captured them. The findings matched those of the Chozo: the Metroids had incredible potential if studied and utilized properly, but were also a danger in the wrong hands.
A group of guerilla fighters known as the Space Pirates made a name for themselves in the earliest days of the Galactic Federation—the galaxy’s governing body, made up of the leaders of many planets—by striking frigates, taking cargo, then disappearing without a trace. Over time, the Space Pirates grew in numbers, their attacks more fearsome, until they became known more for invading and claiming planets, then enslaving the inhabitants. It was this group that heard rumors of a deadly parasite in the hands of researchers on the fringes of the galaxy.
The Space Pirates wasted no time. They’d attacked Galactic Federation ships full of trained personnel; a research station housing civilian scientists was hardly a challenge. With little effort, the Space Pirates came into possession of one of the galaxy’s greatest dangers: the Metroids.
The surviving researchers relayed the news to the Galactic Federation, along with some disturbing details: they’d found a way to multiply the parasites with beta rays, which the Space Pirates learned about. The Galactic Federation rallied their forces and scoured the galaxy for the Space Pirate base, hidden on the remote planet of Zebes. They launched an assault, but the Space Pirate numbers had swelled to such an extent and their fortifications on Zebes were so defensible that the once-mighty Federation had to retreat from battle.
Out of options, the Galactic Federation decided to send in one mysterious Space Hunter, clad in red and yellow armor, who went by the name Samus Aran. Samus was so secretive that most weren’t even sure if the hunter was a man or a woman. A lone wolf, Samus had proven herself through the solo completion of several missions thought impossible, which earned her a reputation for pulling victory out of the direst circumstances. Samus took the job with little hesitation; she had lost her parents as a child to an attack on her home planet K-2L by the very Space Pirates who were now threatening the galaxy. Whether driven by duty, revenge, or the desire to maintain her reputation as the best of the Space Hunters, Samus headed for Zebes.
Once there, Samus infiltrated the planet. Upon reaching the guts of the Space Pirate base, she found the second-in-command, the pterodactyl-like Proteus Ridley, the one who had personally taken Samus’ parents from her. For Samus, Proteus Ridley wasn’t just a roadblock keeping her from completing her mission; this fight was personal.
After a fierce battle, Samus claimed victory, but the fight was far from over. The mechanized nerve center of the base, known as Mother Brain, was still running the Space Pirate and Metroid-cloning operations. For the galaxy to be made safe, Mother Brain had to be destroyed.
As Samus made her way across Zebes toward Mother Brain, the Metroids were cloned and released into the Space Pirate base to stop her. Defeating them seemed impossible—every attack simply bounced off them—but Samus’ cool head and quick thinking led her to discover the Metroids’ weakness: the freezing temperatures produced by an Ice Beam.
What set Samus apart from other Space Hunters was not only her combat prowess and adaptability, but also her Chozo-made Power Suit, which allowed her to rise above normal human limitations. After Proteus Ridley attacked her planet, she was adopted by a small Chozo clan on Zebes. The few remaining Chozo were a far cry from the incredible empire they’d once been, but they carried with them some of the secrets of their ancient ancestors. The Power Suit numbered among these, along with its capability for modular upgrades, among which was the Ice Beam. While the Space Pirates were out pillaging and plundering, they had inadvertently created their own greatest enemy: Samus Aran. Now, decades later, she was not only destroying the Space Pirate generals and their main base of operations, but she was capable of destroying their greatest weapon, a feat considered impossible by those who had come into contact with the Metroids.
Samus eventually reached Mother Brain’s chamber, and the final battle ensued. Pushing her abilities and resources to their limits, Samus persevered until she came face-to-face with Mother Brain. Then and there, Samus dealt the final blow to the Space Pirate leader, ending the conflict that had kept the galaxy’s fate teetering on a knife-edge.