Trunks is the son of Vegeta and Bulma. Mirai Trunks is from the future (Mirai means future). Goku died of a heart virus when Trunks was a baby. All of the Z fighters except for Gohan were killed by the androids when he was still very young. He never knew his father while he was growing up. Gohan and Trunks trained together. Trunks tried to become a Super Saiyan like Gohan. He came close a couple of times, but he couldn't do it. Trunks was pretty much nothing compared to the androids. He fought against the androids with Gohan, but because Trunks was no match for them, Gohan had to watch out for himself as well as Trunks. I love Trunks dearly, and I know he was just trying to help and avenge his father, but he shouldn't have fought.
I think he was more of a burden to Gohan than a help. Anyway, during one battle, Trunks and Gohan almost got killed. Gohan lost an arm and got a big scar on his face. They continued to train. One day, Gohan wanted to fight the androids. Trunks wanted to go with him, but Gohan wouldn't let him. To make sure that he wouldn't follow him, Gohan knocked Trunks out. He flew off to fight the androids. He ended up dead. When Trunks woke up, he went to find Gohan. It was raining when he found him lying in the street. This was too much for Trunks, and he transformed into a Super Saiyan. A few years later, Trunks had a big battle with the androids. He lost, and he almost died. That's when he decided to act on his mother's plan. Her plan was to use a time machine to take heart medicine to Goku in the past. She knew that Goku was a strong fighter. She thought that he might be able to make a difference. She thought that he might be able to beat the androids.
Trunks took the time machine to the past. He fought briefly with Frieza. Frieza had come to Earth with his father as a cyborg. No, Goku did not kill Frieza. He only defeated him. Trunks was the one who actually killed him. Trunks also killed King Cold, Frieza's father. After he did this, he met up with the Z fighters. It was the first time he had ever seen his father. They waited for Goku to come back from space. Once he did, Trunks took him aside and told him about the androids. He also gave him the medicine. Then, he went back to his own time. Unfortunately, Trunks's world was not any different. Apparently, there were now two different timelines. One in which Goku lives, and one in which he dies. Trunks's world still had the androids.
The next time we see Trunks is when he comes to help the Z fighters fight the androids in their time. When he arrived, he said that the androids that the Z fighters were fighting were not the androids from his time. They eventually found the right androids. Then Cell showed up. To fight the androids and Cell, Trunks and Vegeta trained in the Hyperbolic Time Chamber for a year. That's equal to a day outside of the chamber. After his training, Trunks had a big fight with Cell in his perfect form. That's when we see that he found the ability to transform into an Ultra Super Saiyan. It was a very powerful form, but it was also very bulky. All of the huge muscles slowed him down, and he could never catch up to Cell to be able to land any of his punches. When Trunks discovered this, he told Cell to kill him. Cell didn't. He was impressed with Trunks's ability to become so strong in such a short time. He let him go to be able to get stronger. Cell wanted to hold a tournament. So Trunks trained again for one more year in the Hyperbolic Time Chamber. This time, he was alone.
Then the Cell Games (the tournament) started. When Gohan went to Super Saiyan level 2, it was all over for Cell. Cell decided to blow himself up and take the planet with him. Goku sacrificed his life, and took him to King Kai's planet with his Instant Transmission technique. He blew up there instead. One of Cell's cells survived the explosion, though, so he was able to regenerate himself. Somehow, he had absorbed the Instant Transmission, so he used it to get back to Earth. The minute he got back, he shot Trunks and killed him. This made Vegeta mad and he went crazy on Cell. It was the coolest thing Vegeta ever did. Gohan beat Cell, and Trunks got revived by the dragon balls when the Z team wished all of Cell's victims back to life. Trunks went back to the future the next day.
Because of all of his training in the past, Trunks had no trouble defeating and killing the androids in his time. Later, he also killed the imperfect Cell, thus ridding his world of the evil androids forever. That is the last time we see Mirai Trunks.
Race: ½ Human, ½ Saiyan
Power Level: The only power level given for Mirai Trunks was his suppressed power level when he first arrived in the past. It was five.
