DBZ Fan Fic for post Majin Buu SL. (Assuming DBGT never existed)
I'm not a hardcore DBZ fan, but it is a guilty pleasure and good for killing boredom. An idea popped into my head a couple years ago and though I don't have any intention of doing a project based on it, I thought I'd throw the idea out there for the hell of it. This story is taking into account that the DBZ movies involving Brolli aren't cannon and are a seperate universe unto themselves.
Since continuity in the DBZ storyline (with movies and what not) is pretty much a mess and can be torn apart with a little bit of reasoning, I'm not going to worry about any possible holes that might pop up (I'm certainly not a DBZ encyclopedia).
The main villain of this saga is Brolli, a character who kind of got the shaft after the first two DBZ movies involving him. While Goku is on earth during the DB era, Brolli is out terrorizing the far universe, destroying planets, eradicating the alien races that reside there. One planet of highly advanced people is being attacked by Brolli and in order to save their species and find a way to possibly combat this menace in the future, they send out several of their youth in space pods to different parts of the galaxy. Well one of them ends up on earth, and since the boy looks practically human in appearance, he's adopted after he wanders into civilization from the wild. Knowing what his purpose is, he trains as a fighter, and a couple years pass by. Eventually through rumors or local folklore he hears about Korin's tower and the lookout at the top where Earth's guardian stays. Well a long story short, the boy is determined to climb the tower and find Kami at the top, hoping that the guardian will aid him in becoming stronger so that he can destroy Brolli. Eventually through hard work and sacrifice he makes it to the lookout, yet cannot immediately find anyone. As he wanders about he comes to the main building on the lookout and overhears Kami and PoPo talking, and learns about the room of spirit and time. Theoretically it sounds like a wonderful idea and with a little bit of stealth, the boy manages to sneak into the room, unaware of the potential danger. Once inside, the boy trains for a good deal of time, though eventually he wanders to far and becomes lost in the nothingness. Using DBZ logic (which means nearly anything goes), he gets to a certain distance away from the door and his bodies aging process slows down, as does his metabolism, eventually to the point where he's practically frozen at a certain time and space. Unfortunately for him he's alone in a vast white void. Stuck in this hell of sorts he trains, his anger and despair fueling him, and for the moment he ceases to exist as far as the outside world is concerned.
Fast forward to the training done by Goku/Gohan and Vegeta/Trunks. The power they give off is like the tiniest blip on a radar when it comes to his sensing spiritual energy, and now for the first time in what seems like ages, he has a sense of what direction will lead him to freedom. He continues moving towards that source of energy, and time continues.
Fast forward to the fight with Majin Buu and Gotenks in the room of spirit and time. This incredible power pushes him harder and harder, and he arrives what seems like moments after they leave, but in reality the fight with Kid Buu in the outside world has already come to a conclusion. Arriving at this vaguely familiar scene, he collapses from the sudden change of environment, as his bodies functions and requirements start to return to what they normally were. He comes to his senses and sees that the door is destroyed. Though he feels defeated in one sense, he's glad to be alive and begins the path of rehabilitating himself from the trauma he experiences from his intense training. Eventually he is healed and manages to find a way out of the chamber. Back on earth, he is initially drawn to the idea of seeking out Brolli, but since he felt a strong power source before, he knows that there must be strong fighters on earth, whether good or evil. So he lays low, keeping his power hidden as much as possible, waiting for these powerful fighters to reveal themselves.
Things in the Z fighter's world go back to normal until Brolli arrives and starts raising hell. He feels the same hatred towards Goku as we see in the movies. The Z fighters try and defeat Brolli, but even Gogeta and Gotenks are unable to subdue the powerhouse. Observing the scene from seclusion, the boy (who now looks like a young man of twenty) senses this dreadful power and knows in his gut that this is the Super Saiyan of legend that terrorized his home planet. Coming to the aid of the Z fighters, this mysterious young fighter stands toe to toe with Brolli and manages to remain in one piece. His training has made him a master of defense and counter attacks, but not as great of an offensive powerhouse as the Saiyan fighters. The fight draws on (as most DBZ fights do) and the Z fighters have to come up with some solution to get rid of this menace since the young fighter can't go on forever. Eventually someone hits upon the possibility of fusion ala Gotenks or Gogeta. However seeing as there's a snowball's chance in hell of getting Brolli to do the fusion dance, they decide that the Potaro earrings are the only choice. Eventually through Dende talking telepathically to the young fighter, he realizes the plan and once the earrings are brought he puts one on and then after some intense fighting manages to secure Brolli in a grappling hold so that one of the Z fighters can fasten the earring to his ear. Given that the young fighter endured the mental strain that the void put on him, his self discipline and focus is second to none. This is the edge he'll need to keep Brolli's personality from taking over. The fusion happens and we see a new fighter emerge, something like a Super Saiyan to the hundredth power.
With Brolli's rage bottled up for now, things are back to normal on earth. However there is a war raging within this fighter, one that he manages to win for the time being. However in the future it begins to take a toll on him, and with the introduction of Paragus, who we know is the one using Brolli as a tool of destruction, things get even worse. Eventually Brolli becomes too much to handle and the fusion dissipates and the fighters separate completely. Now the Z fighters have to figure out how to finish Brolli once and for all, especially given that Brolli gained power from the fusion.