Should the player find all the Ancient Codices, it would be revealed that Fuse was the personification of Planet Fusion who ruled over the Fusion race. At that time, Fuse looked for masters who can teach him on how to improve his civilization. Those masters were the first Dragon Guardians. The Guardians, happy to have a pupil at last, brought him to Ninjatana, the capital of the mythical world. Fuse was a quick learner who excelled above his peers. He was appointed the position of Genius Loci, the rank of guardian of a planet.
However, Fuse became ambitious and power-hungry, believing that he can use the knowledge he learned from the first Dragon Guardians to be a multiversal conqueror. Calling himself "Lord Fuse", he amassed his Fusion Army to conquer worlds. He declared that he will be the only one who would bring order to chaos, and that he will do so by assimilating all in the universe with Planet Fusion. No world could stop him, until the Dragon Guardians and their allies fought him. They used the "Dimensional Sealing Formation" to send Fuse and Planet Fusion back to their galaxy. Fuse swore revenge on the Guardians and somehow was able to escape his galaxy after the first Dragon Guardians retired.
At some point before coming to Earth, Fuse invaded the planet Anur Phaetos, the home planet of the Ectonurites, the same race as Ben's alien form, Ghostfreak. Eventually, the Ectonurites reached an agreement with Fuse; their planet was spared, but they had to aid him in his conquest. Only Vilgax seems to know anything about this agreement. At some other point Fuse also tried to invade the homeworld of the Glorft, but was repelled. Eventually, Fuse entered our Solar System and invaded Pluto, Saturn, Jupiter, Venus, and Mercury (and possibly Neptune, Uranus, and Mars as well). Fuse now has his sights set on Earth, beginning his invasion of our world.
For most of the war, Fuse acts from behind the scenes, on Planet Fusion. From there, he leads his troops against the Earth's forces and makes his plans and strategies for consuming the world. He has also tried on numerous occasions to study Imaginary Energy, the element that is most effective against his forces. It is not until the mission "Fuse No More (Part 1 of 4)" that Fuse starts personally to participate in the war.
By manifesting a physical form on the surface of the planet, he planned to transfer his energies down to that form, allowing him appear on Earth, destroy the hero, and power up his forces from inside Fuse's Lair. Fuse eventually managed to materialize himself fully in this form, but thanks to the hero, the shield that protected him was destroyed, thus leaving him vulnerable. In "Fuse No More (Part 4 of 4)," the hero faces Fuse and is able to destroy his form after a long difficult battle. However, because the form in his lair was only an inferior manifestation of Fuse himself, Fuse's energies simply returns to Planet Fusion upon his defeat, and he is able to continue the invasion and his plans as he did before.
In The Future, Fuse has somehow achieved the dark powers of Dark Gaia, a monster sealed in the earth. This is how Fuse got his new monsters. The first victim of the monsters was Shadow the Hedgehog.
After the heroes founded the Academy, Fuse reorganized his forces and created several new monsters to keep a handhold on the war.
Powers and abilities
Most of Fuse's powers is unknown, due to the limited knowledge about him. In battle, Fuse constantly keeps changing his attributes, from Adaptium, to Blastons, to Cosmix and back to Adaptium. This way, Fuse makes it harder for the player to select the right Nano to fight him with. Over the millennia, Fuse has mastered many different forms of science, magic and technology as a result of his world-conquering.
Fuse in his incomplete form has the same different powers as his Fusion Monsters, such as stun, corruption attacks and eruption attacks, but they are much stronger that normal. He is also the only fusion in the game that can - Self Heal himself. He mainly uses mêlée attacks and can fire blasts from the limbs attached on his back.
His most well-known power is his ability to create Fusions, evil duplicates of the Cartoon Network Universe's inhabitants, by combining a personal item with Fusion Matter. These efforts, however, drains Fuse of his energy and thus it takes time for him to replace Fusions that have been defeated in battle.
According to Samurai Jack, Fuse's power pales in comparison to Aku. However, as Fuse prepares to materialize on Earth, Samurai Jack himself openly claimed that all hope would be lost if he did, and that he was unsure if they could win.
Fuse is one of the strongest monsters in the game, surpassed only by Don Doom, Bad Max, Fusion Kimchi, the turrets inside Vilgax's ship, and the Fusion Blowfish, Beauty, Rudy, Cootie, Judy, and Tootie, all of which possess surprising defensive power.
Shatterguns and rifles are recommended for battle with Fuse, as his more powerful abilities are triggered by moving within a certain distance. Both types of weapons can harm him beyond this distance. Damage and healing Nanos are also recommended, as Fuse's stunning and healing abilities in the first and second forms, respectively, can make overcoming him difficult. Specific Nanos would be Leech, Health, and Freedom, though the latter Nano is recommended only for the first two phases.
Fuse's manifestation is fought in three stages: his first body, his second body and right arm, and his third body and left arm. Each body and arm spawn with the defeat of the previous body. Defeating the final body counts as victory even if the arms are left "alive." Fuse's body is rooted to the ground, and cannot move. The arms, however, are able to move. Fuse's body changes type each time it is defeated.
If the player moves within pistol range of Fuse, his corruption and eruption attacks have the potential to be triggered. His eruption attack, in particular, covers most of his throne and will instantly KO the player regardless of health. Staying at rifle range prevents their use, though Fuse can still use his body's abilities. Fuse's arms each possess the ability Fuse had in the previous phase of battle and can attack the player physically.
Fuse's body's attacks consist of a simple mêlée attack, a more powerful corruption attack, and an eruption attack which instantly knocks out anyone on his platform. Unlike other monsters in the game, Fuse does not heal when the player is knocked out, unless he has the heal power.
The player begins by fighting his main body, which has the stun ability and a quick mêlée attack. Once that is defeated, his right arm detaches with the ability to stun and his body gains the ability to heal; both parts have their own mêlée attack. A shattergun will allow both to be struck at once. Thanks to his healing ability, Fuse's body will likely take a significant amount of time to defeat. His final body causes his left arm to detach with the healing power and his body gains the damage power; both have a mêlée attack as before. Players will achieve victory after defeating the body a third time.
Frost the Hedgehog's Continuity
At some point, Spongeglob (Globoulous' favorite form) is patrolling space. He rains down on Planet Fusion, making many Fusion citizens become Glob Minions. Lord Fuse battles Spongeglob, who, along with Fuse, has been in the universe for millions of years. Spongeglob finally wins, and Lord Fuse is destroyed along with Planet Fusion. However, when Earth receives this news, Spongeglob then explodes and dies, exposed to too much Fusion. Everyone is in sorrow. However, players can still play the game, as when Fuse died, Slade took the army, creating the Fusion Resistance. He sends the clone army back to their universe, along with all of the Star Wars characters in the game. After this, the player gets many new missions, and the game continues, as even when Slade is defeated, Dexter explains that traces of Fuse and more are still on the planet, and will take at least a year or more to clean up, along with Fuse's army remains.
This is because Fuse can regenerate almost instantly, and the Fuse defeated previously was simply a form of it. It is impossible to destroy Fuse permanently without destroying the entirety of Planet Fuse. As such, the rather large story arc ends with Fuse taking the 'army' back.