Days later after Trunks and Gohan had their butts kicked by the two wind up toys, Trunks started talking to Gohan on how would he be able to become a Super Saiyan. The answer Gohan gave was "Great Motivation". Suddenly the Androids went on another killing spree. Furious Gohan went SS and knocked Trunks unconcious so he wouldn't get hurt in the battle ..or prehaps lose his life.

Gohan fought hard but was killed in battle. Trunks heard the loud cries of pain and awoke. (This is a tear jerker :( )

Trunks finds Gohan in the rain...lying face down in a puddle of water..dead. Enraged the young hero turned SS! Three years later Bulma built a time machine that would hopefully restore peace to the era they lived in.
Trunks now 17, constantly argued with his mother that it wasn't nessecsary for the use of time travel to help restore order in the future. To prove that he was right Trunks set out to Pepper city..(the most recent attack site of the Androids)
Trunks was far too weak and he got his butt was kicked..severely. Bulma found him and placed him in the hospital. When Trunks awoke he agreed to use the time machiine and warn Goku and the rest of the group of the horrors yet to come.

In the Past Trunks single handedly destroyed Frieza and King Cold. Trunks waited with the Z-warriors until Goku arrived from Space. Once he Spoke with Goku Trunks returned to the Future..hoping that Goku could make a difference.
Once Trunks had returned to the Past to see if Goku had saved the world..all Trunks saw was destruction. He finally caught up with the Z-fighters and saw that the Androids they wer fighting weren't the Androids in his time. Infact it was Dr.Gero and some dorky looking Android. Dr.Gero fled and Trunks,Krillen,Yamcha,Tien,Vegeta and Piccolo began to search for him and his secret lab where the real Androids were.

Vegeta and Trunks did not get along well at all..Vegeta always yelled at Trunks and punched him so he wouldn't interfeer with his training (nice guy huh?) Even though Vegeta was a jerk to his son,Trunks still loved him and sacraficed a lot for him in order to please his father. When Trunks and Vegeta trained in the Hyperbolic Time Chamber they slowy began to understand eachother better.
Trunks had advanced to SSJ Ultra while training but did not let his father know since he did not want to hurt his pride.As Trunks and Vegeta emerged..everyone was shocked at how different Trunks looked. His hair was long and he was much taller than before. Vegeta and Trunks had encountered Cell in his third form. Trunks saw that Vegeta was going to let Cell absorb Androoid 18 and he tried to prevent his Father from doing so. Trunks was unsuccesful and Cell had then and there become complete.
Cell was amazingly strong and he easily defeated Vegeta..seeing his Father down and out brought Trunks to his Ultra Form. But even he wasn't strong enough for Cell.Cell spared Trunks so he could warn his friends about the Tournament he was going to hold in 10 days.
When the contest finally started..it turned out to be a disaster. Goku had died,Gohan was fighting and his father wouldn't stop telling him to shut-up.And as if things couldn't get any worse Cell came back and Killed Trunks with a Ki blast!(poor Trunks..sniff)

But he was revived later with the DragonBalls (YAY!!) As Trunks and Yamcha were heading out,Yamcha told him that when Trunks died,Vegeta went mad and defended his son. Trunks couldn't beleve what he had just heard. The next day Trunks left home for the Future (sniff..sniff) so he could finally take back what was left of his.
At home Trunks defeated the Androids with ease since he was so strong and even Cell didn't stand a chance. Once Trunks defeated the monsters of his world he looked up to the sky and thanked Vegeta,Gohan and Goku. This is the last time Future Trunks would ever be seen in Dragonball Z.