The sky was a dirty grey colour, with the ground a uniformly dead brown. As far as the eye could see, there was no major life on the surface, save for a few scraggly trees that looked half-dead anyway. For earth, this would be cause for major concern, a regression back to the pollution that plagued humanity nearly a thousand years before.
This planet was not earth. This planet, to be honest, didn't have a name. On star charts, it was designated 'SR388'. And it was also quite quarantined. No one could set foot on the surface without express permission from the Galactic Federation. So, ugly as it was, the landscape was a sight that few ever got to see.
And yet, one of the people seeing it right now would be happier to never see it again.
Years ago, scientists landed on the newly-discovered planet to collect life form samples. All went well for the first few days, with no real breakthroughs, just creatures that would only be vaguely interesting to anyone who wasn't a xenobiologist. Amongst other things, it was discovered that there was once a substantial city there established by an ancient civilization that had not been sighted for thousands upon thousands of years. And then the scientists found them. They looked, basically, like jellyfish. Flying jellyfish with visible brain nodes, yes, but 'like a jellyfish' was the most apt description. To put it lightly, the scientists were unable to take one as a sample. To put it in greater detail, the man who first stumbled across one attempted to capture it, and it suddenly lunged at him. Unlike a jellyfish, the bottom of the creature didn't have many soft tentacles; it had two sharp, piercing spines. It injected these into the man's back, clung to him using some hooks that bordered the spines… and drained his life energy. Not his blood, not his muscles. It's never been quite clear what, exactly, they do to a victim when they kill it. What is known is that the poor sap's life was drained away, and his body collapsed into a cloud of dust when it released him. However the food chain on SR388 is arranged, these things are definitely at the top.
A few scientists managed to escape, and report their findings to the Federation. A band of the monstrous, murderous, and dangerously intelligent beings known as Space Pirates intercepted the broadcast, and realized that the creatures, which were, according to a translated hieroglyph on one wall in the city, known as 'Metroids', could be the most powerful weapon any force had ever known. The pirates landed on SR388, somehow managed to capture some Metroids, and brought them back to their base of operations, the planet Zebes. The Federation was not exactly thrilled with this turn of events, so they hired the best bounty hunter in the quadrant to exterminate the base and destroy the Metroids. They hired Samus Aran.
Samus Aran had very few happy years. She lived in a space colony designated 2KL for the first six years of her life, until disaster struck. The Space Pirates, led by the monstrous Ridley, chose 2KL for their next target. They butchered the inhabitants, stole everything that was valuable, and destroyed most of what wasn't. But, somehow, they missed one survivor. They missed six-year-old Samus Aran, who was hiding in a small cabinet, crying and trying desperately to remain utterly silent. That, and trying (and failing) to remove the images of destruction and death from her mind. When the Federation's soldiers finally showed up, there was nothing left. What they didn't know was that members of the incredibly ancient race no one had ever seen, the Chozo, had arrived before them, and retrieved the little girl. They brought her up on the planet Zebes, where one of their cities was left. They raised her as one of their own, yet while the Chozo were well known (to those who knew of them at all) as pacifists, they raised Samus to be a mighty warrior. To help her in her journeys, they instilled in Samus some of their own blood, making her stronger, faster, and generally more physically fit than the average human. They also gave her a special Power Suit that increased her attributes further, and allowed her to withstand damage that no human armour could have survived. It was about six and a half feet tall, with a red helmet and green visor. The inside of the visor gave Samus a constant view of her vital stats: the integrity of the suit's armour, the amount of missiles she had left, and a small map in an upper corner that could be expanded for a view of the entire locale. The body and legs of the suit were yellow metal, with a green sphere in the back of the left hand that could light up the area. With the Varia suit upgrade, the body changed to orange, with large 'shoulder pads' and sharp spikes projecting above the shins. Finally, the Gravity suit upgrade would make the legs and arms purple, while unchanging the colours of the chest. The right hand of the power suit was a variable cannon that could fire either a variety of energy beams, or a limited supply of missiles. The suit itself was modular, in that if Samus could locate various Chozo-made upgrades, she could make the suit more versatile. For instance, the Varia suit upgrade made the suit resistant to extreme heat. The wave beam upgrade made the gun strong enough to shoot through solid objects. And the high-jump boots improved Samus' already considerable jumping skills with a pneumatic push-off.
Eventually, Samus was a powerful force to be reckoned with. And an unusual one. For someone who was so severely traumatized, at such a young age, she was surprisingly unlike the other bounty hunters. She would, for instance, never take any job that required her to kill children. She would never take a job without first doing extensive research on the target. If she didn't feel the target deserved death, she wouldn't do it. Finally, if the job focused on killing Space Pirates, then no matter how low the pay, no matter how high the risk, she would take it, virtually no questions asked. The Chozo had done a good job of healing her damaged mind, but no one could ever expect anyone who had gone through that to ever be fully healed.
I won't bother to go into detail with her exploits on Zebes. They are, after all, legend. She successfully completed the mission: Destroy the Mother Brain, eliminate her lieutenants Kraid and Ridley, (against whom Samus had a personal vendetta) and stop the Metroid operation on Zebes.
A relatively unknown escapade involving a powerful mutagenic called Phazon, some genetically-altered Metroids and a recently revived Ridley followed on the planet Tallon IV, which Samus came out of on top, more powerful than ever.
Samus had decided, after this, that the Metroids were simply too powerful to continue to survive. They had to be eliminated. After proposing her idea to the Galactic Federation, they allowed her to single-handedly go to SR388 to combat the Metroids on their home planet. And in this, too, she succeeded where all others had failed. She destroyed every Metroid on SR388, in all their states of growth, (Metroids grow bigger and more powerful when exposed to Gamma radiation.) including the truly monstrous Metroid Queen. All of them - except one. Just before Samus left the planet, the last remaining Metroid egg hatched before her eyes. Her initial reaction was to destroy it… but it didn't even try to harm her. As the first being it encountered after being hatched, Samus had become its 'mother'. Samus couldn't bring herself to kill it, even knowing what it might someday become.
She brought the last Metroid back to the Galactic Federation, and left it in the care of Ceres Lab, a scientific research station. Unfortunately, Samus hadn't even left the solar system the lab was located in, before she got a distress call. She returned to Ceres, only to find the entire crew dead, and to encounter Ridley, the perpetual thorn in her side, stealing the last Metroid.
Samus followed him to Zebes, where the Space Pirates had secretly been rebuilding their base. Although she succeeded in killing Ridley and Kraid once more, during the titanic battle with the reconstructed Mother Brain, the last Metroid gave its life to protect its 'mother'. The Mother Brain killed the Metroid, and an enraged Samus fought harder than she had ever fought before. Something in her had changed. She had fought before for vengeance, but now she was almost bloodthirsty. She escaped Zebes before a massive self-destruct device vaporized the entire planet, but at least the Pirates would never again be able to use the Metroids as a weapon. Which brings us to the present day.