The Story of Futre Trunks
Androids 17 and 18 were released. Android 17 killed Dr. Gero and then began their reign of terror. Goku suffered a heart attack. Without the proper medicine, Goku died. Without Goku, the Z warriors were too weak to stand a chance against the androids. In turn, Vegeta, Yamcha, Tien, and Krillin were killed in battle. Chaos wrecked everywhere. Cities were destroyed by the androids. Many were killed.
A Few Years Later...
Trunks is now a teenager and Gohan is grown up. Master Roshi, his turtle, and Oolong spent their days hiding in a submarine. Chi-Chi and the Ox-King lived in fear and mourn over Goku. Bulma learned how to live the terrible environment and goes about her everyday business. Anroids 17 and 18 continue to destroy everything in their path. The humans tried calling the army, but all the federal troops have already been killed by the androids.
Trunks is riding home with Bulma. There is a radio report about another disaster the androids caused. Trunks becomes angered with rage at such injustice. He flies off to the devastated city and anger continues to build because he knows there is nothing he can do; he knows that he is too weak to fight the androids. Gohan descends in front of Trunks and agrees to train Trunks. The two head back to Bulma's house to start training.
Gohan and Trunks spend days in training. Gohan is trying to teach Trunks how to reach Super Saiyan level, but Trunks cannot, despite all his anger. Trunks gets distressed, but Gohan continues to encourage Trunks. Meanwhile, Androids 17 and 18 continue their destruction of the world.
Gohan and Trunks decide to face the androids. Gohan is standing up against Android 17, but Trunks is getting kicked around by Android 18. Gohan flies over to aid Trunks and has to fight both androids now. The androids throws huge fireballs at Gohan and Trunks and fly away. Gohan wakens and struggles to get his body over to the unconsicous Trunks. Gohan is badly injured and lost an arm in battle. Gohan finally reaches Trunks, struggles to get to his bag of senzu beans, and discovers that there is only one piece left. He feeds it into Trunks' mouth and collapses. Trunks awakens and quickly gets Gohan back to Bulma.
Gohan recovers, but is missing a limb now. He continues to train Trunks, but Trunks still cannot reach Super Saiyan level. Days go by, and the androids are still destroying the Earth.
Gohan and Trunks decide to face the androids again. Trunks feels ready to go, but Gohan hits him in the head and knocks him out. Gohan knows that Trunks is still not ready, and goes to fight Androids 17 and 18 himself.
Trunks awakens and discovered what has happened. He quickly flies over to the city the Androids were in. The city is destroyed, and Gohan is lying on the ground....dead. There is a storm. Rain is falling hard. Trunks looks at the dead Gohan and becomes enraged. He screams and finally reaches Super Saiyan level.
Trunks decides to fight the androids again and encounters them. He quickly discovers that even though he is in Super Saiyan form, he is still no match for them. The androids kick Trunks around and everything slowly goes blank.
Trunks awakens to find himself bandaged in his bed. Bulma had taken his body home. Bulma tells Trunks that she has been working on a time machine and tells Trunks to go back in time to before Goku had his heart attack. Bulma gives him heart attack medicine for Goku to prevent his death so that the whole future would change. Trunks agrees. He gets in the time machine capsule that has the word "Hope" painted on it and travels to the past. Bulma waves goodbye and wishes him good luck.
Trunks Story ends Here,but the rest is told below
Trunks traveled back to where the ending of the Frieza Series took place. He kills Frieza, his father King Cold and all of their crew and introduces himself to the Z warriors. Here is where we first encounter Trunks in the Dragonball Z series. Vegeta thinks that he cant be a Super Saiyan because he has Purple hair but he is. Everything we know of him happens. He gives Goku the heart attack medicine that Bulma gave him and saves Goku's life. Then, he trains with Goku and Vegeta. It is now the Cell Series. Trunks (now known as Future Trunks because the Trunks in the timeline we know of is a baby) joins the struggle against Cell. Cells kills Trunks, but Trunks is resurrected by the dragon balls. Trunks, now even stronger from all the battles and training, heads back to his time.
To his dismay, nothing in the future was changed. However, he is a lot stronger now. He confronts the anroids of his timeline again and easily kills them now. Then, he sees Cell in his first form and easily kills him too. There is peace in his timeline now.
In another timeline, Future Trunks used the time machine to get a device to destroy Androids 17 and 18. Cell was finally developed from the remains of Dr. Gero's lab and killed Trunks. Then, he stole Trunks' time machine and traveled back in time to the timeline we know of. That is how Cell existed. In Future Trunks' timeline, Android 16 was never released because Dr. Gero was killed befor he could activate him. There is no explanation on how Trunks acquired his sword. Movie 13 was made a while later and trys to explain this, but the sword was only given at a time where the world was not threatened by the androids.