Trunks is Vegita's son. In his future, all of the Z fighters were killed
by the Artificial Humans, except for Goku, who died of heart disease.
Trunks travels 20 years back in time to give medicine to Goku so he can
survive this disease and defeat the Artificial Humans. Trunks' returning
in time alters the past in other ways which can be seen later.
After giving the medicine to Goku, Trunks goes back to his own time, but
returns again three years later to help the Z fighters battle the
Artificial humans. During this time, he becomes extremely powerful and
surpasses every other one of the Z fighters except for Gohan and (maybe)Goku.
