Trunks first appeared after the Garlic Jr. Saga. Trunks had a terrible past and as a result, he became more disciplined and mature then his predeccesor Chibi Trunks. When Trunks was a baby, the androids 17 and 18 had killed all of the all of Eath's Special Forces except for Gohan. To save the rest of the world's inhabitants he is forced to train and fight back.

Trunks is the son of Vegeta and Bulma and sister of Bra (a character in GT who acts like Marron but more considerate of other peoples feelings). Trunks is the only son therefore Bulma became very protective of him. Trunks had only reached 2 stages of the legendary transformation, SSJ. The death of Gohan, his master (in the future), trigger his first form but he was still not strong enough to beat the duo 18 and 17. Searching for new hope he was told by his mother that if only Goku was there to help they wouldn't live in fear.

Trunks beleived that he would learn something from Goku so he decided to go back to the past and save Goku although he thought the mission was pretty stupid. But that wasn't the only reason for him to venture into the past, he also wanted to see how his father was like.