Zarm's History
Before the show
Zarm was once the Spirit of Earth but left the planet. It is clear that he and Gaia are enemies, although the details of their conflict prior to the show are never spelled out. According to her, once banished, he searched for other worlds to influence and caused at least one to destroy itself in a nuclear holocaust. It is unknown how many planets he has influenced; it is possible the world Gaia referenced was only one of many he destroyed.
Interestingly, in Scorched Earth Zarm is revealed to be the influence behind the dictator Morgar, and claims to have been "a part of every important tyrant in history". If true, this would mean Zarm has continued to stay active on Earth long after his original departure, over a period of many centuries before the present day.
Season 1
Pretending to be a benevolent alien, Zarm claims he comes from a world of advanced science where hunger, cancer, and other scourges are long gone, and says with his help Earth can soon reach such progress. He tricks the Planeteers into trading their rings for more powerful weapons, which he provides. Ma-Ti, whose ring's power cancelled out the mind control, is the only one who doesn't trust him. Zarm then turns the Planeteers away from Gaia with literal "Iron Fists" that increase their elemental powers a hundred-fold, making Gaia mortal and allowing him to nearly kill her. However, his plan for staging a nuclear war on Earth, with the Planeteers' unwitting help, is thwarted by Gaia, who manages to stop the Planeteers from using Zarm's powers they possess by showing that his planet's advanced science was put to use in war, leading to its destruction. Unfortunately for Zarm, his "conquerors" then abandon him and restore Gaia as a spirit, while he is sent back into deep space by Captain Planet.
Season 2
Zarm forces all the other eco-villains to work together under his command, in order to wreck the Earth Summit.
The Earth Summit (based on the real-life Earth Summit in Rio de Janeiro during June 1992) is being held, and the Planeteers are sent there to make sure the Eco-Villains don't try to spoil it. All six Eco-Villains have gathered to make plans, but are surprised by the arrival of Zarm. He forces all the villains to work for him; when Blight protests, he attacks her with an energy blast and she quickly submits. They begin a plan to kidnap delegates and replace them with duplicates who support pollution (Including Dr. Blight and Looten Plunder,Who put on helmets and shapeshift into the clones of delegates through Zarm's technology),while Zarm masquerades as the Brazillian president. The Planeteers follow the disguised Zarm back to his ship and discover what is happening, but are swiftly captured. They're able to escape briefly, but Zarm poses as Gaia and tricks them into handing over their rings, letting him capture them again.
Seeing all this from Hope Island, Gaia directly intervenes and teleports directly to Zarm's ship in an attempt to rescue the Planeteers. Zarm declares that he will destroy his old enemy, and a battle between the two spirits begins. At first the fighting favours Gaia, as she is able to withstand and neutralize Zarm's attacks with ease. However, Zarm puts the Planeteers in danger and forces Gaia to rescue them. This leaves her vulnerable and allows him to deliver a blow that wins the fight by destroying the crystal Gaia is in, leaving her powerless. With this, Zarm uses his powers to transform Gaia into an old woman.
Zarm reveals to the Planeteers that because of his victory over Gaia, ten years have passed outside the ship. Earth is now horrifically polluted, and the Eco-Villains have a free hand to cause as much destruction as they please. Zarm allows the Planeteers to freely leave his ship, but not before blasting Gaia and announcing that she'll turn to dust in twenty-four hours. Desperate, the Planeteers search for Commander Clash, whom they first met in their struggle against Captain Pollution. He is revealed to still be active in resisting the Eco-Villains; he tries to stop Sly Sludge and Hoggish Greedly, who are clearly aware of him and have apparently faced him before, from polluting a beach. He is defeated, but the Planeteers arrive just in time and rescue him.
Clash and the Planeteers come up with a plan to attack Zarm's ship, and Clash actually manages to trap Zarm in a restraint chair, but Zarm uses his powers to break free and drive Clash off. Feeling defeated, Clash offers to take the Planeteers to safety on his island, but they refuse. Zarm and the other Eco-Villains then capture the Planeteers, and Zarm mockingly has the Planeteers "fight" him. He allows the Planeteers to have their rings back, and then one by one, each Planeteer is freed from a force field and allowed to try and resist. Zarm's powers easily defeat each attempt, but the fact that he gave the rings back ends up backfiring severely when Clash comes back and restores Gaia to normal. With the rings in their possession, the Planeteers are able to summon Captain Planet, who is especially angered by how close Zarm came to killing Gaia and the Planeteers. Planet forces Zarm into his ship and sends it back into deep space, then brings Gaia another crystal from Hope Island that allows her to restore the timeline.
After the Planeteers get arrested by Commander Morgar’s soldiers, they are brought before the dictator himself. They get taken by surprise when Zarm emerges from Morgar, revealing he had been possessing the dictator the whole time and directing his actions. Zarm also revealed this was not the first time as he had been a part of every dictator and tyrant in history (save for one). He brags that the Planeteers are helpless without their rings and that he planned to use the rings as weapons for conquering Pacifa, until Morgar points out there are only four rings. This angers Zarm when he finds it to be true and that the Water Ring was missing. He demands Gi to tell him where she hid her ring, who naturally refuses. Zarm then forces her to talk by locking her in a suspended cage while the other four Planeteers are shackled in a deep pit slowly filling with water, threatening to drown them if Gi doesn’t give up her ring’s location before leaving.
Thanks to a reformed General Baaz, the Planeteers escape and steal back their rings behind Zarm’s back. Zarm panics once Captain Planet is summoned and undoes his damage by putting out all the drill fires. Morgar’s soldiers also flee in panic, leaving the cowardly dictator to his fate. He desperately asks Zarm what they should do now, to which he coldly responds Morgar has two choices: he could go to jail for his crimes, or he could lock himself in his fully-stocked bomb shelter to live out the rest of his life. Morgar takes the second choice and retreats into a hidden elevator, asking Zarm if he’s going to come as well. Zarm refuses, saying he doesn’t plan on going down with the ship.
Zarm would then go to another country and appear in the office of another corrupt leader who had citizens pounding at his door. He possesses the leader, offering to help him take over the country with an iron fist with a little strategy, scorched earth. Before Zarm could try anything, he is taken by surprise by Gaia’s sudden appearance, who tells him that no matter where he goes, she and the Planeteers will be there to stop him.
