Trunks, son of the last of the royal Saiyajin bloodline and a super intellectual mother. He was introduced near the beginning of the Jinzonigen Saga when Bulma wanted to see the technologically advanced jinzonigen and took her baby with her. For the beginning part of Trunks' life, he had little or no impact on the series until post-Cell Saga when he was older. He was then introduced when Gohan went to Bulma for a super hero custume.

Unlike his future counter-part (whom he wasn't old enough to remember), Trunks was not born in a future of death, his younger days were much happier and peaceful after the years after Cell's game. Trunks takes after both his parents. He is very smart for his age and he is also the toughest little kid this side of the galaxy. He also has remnents of Vejita's trademark long sloping forehead.

Like Goten, Trunks was able to acheive Super Saiyajin at a young age. I don't believe they mentioned how Trunks first transformed, the first time we see this is when he is training in the gravity room with his father (who was SSJ at the time). Trunks was unable to do much of anything in the high gravity environment (I think it was 150 G; I can't read Japanese but Vejita says something about 150 in the manga), so Trunks decides to transform. Vejita sensed something was up the moment before he transformed into a Super Saiyajin, and then the look on his face while Trunks ran around the room doing somersaults was absolutely priceless. In fact, I'm bored enough to scan it in.

Trunks met up with Goten somewhere during those several years of peace, although we first see them talking together in the Tenka-Ichi Bodukai. They both trounced (and humiliated) their opponents, until the final battle: Trunks Vs. Goten. Both of them were very evenly matched. In the end, Goten went out of the ring, and Trunks won (Yes, Vejita made a comment about this to Gokou, very funny).