Vegeta: He was the prince of all Saiyans and was sent to destroy another planet when Freezer blew up Planet Vegeta. He grew up and became one of Freezer's men without knowing that Freezer was responsible for the death of his father. He soon realized the truth after he turned his back over Freezer while trying to find the Dragonball in Planet Nameck.Vegeta nearly killed Songoku over the battle on Planet Earth.After the battle with Freezer on Planet Nameck, Vegeta followed the earthlings back to earth and made a Family there and became a good guy.( well, he didn't became a good guy right away but I just want too shorten his life story up, hehehe). Second Saiyan to become a Super Saiyan.

Songohan: Don't mix up your head by telling yourself this is man that found goku when he was a little kid. This is Goku's son . Son Goku married Chichi and had a son. Gohan was a nice little kid . He was kidnapped by Raddizt who wanted Goku to join Vegeta to destroy another planet. But as always Goku  saved the planet. At a very young age Gohan managed to beat Cell in the form of a Super Saiyan 2 .He grew up and married a girl named Videl and had a daughter named Pan(I'll tell you his married life later). Gohan's inner energy was brought out which enable him to use all his energy without becoming a Super Saiyan.He was the first Saiyan to become a Super Saiyan 2 and the third to become a Super Saiyan .

Piccolo : Piccolo was Piccolo Daimon's son. He was first a bad guy but he started to turn into good guy when he had to join forces with goku( I'm starting to sound like a star wars movie) to defeat Raddizt .Piccolo teach Gohan how to fight after Goku's death .Piccolo helped a lot during the battle with  Radditz, Vegeta, Freezer, Cell and Majin Buu. He assimilates himself with Neil(a nameck) and later on with his half . He was also the strongest Nameck ever lived. His weakness is at his tentacles and his ears.

Songoten: This is Songoku's other son(the smallest). This boy was just like his father. He had the same hair style, behavior ect. He tuned into a Super Saiyan when he was a little kid. His best friend is Trunks( Vegeta's kid). He helped a lot during the battle with Majin Buu which he fused with trunks to become Songotenks.

Trunks: Well, Vegeta came to Earth and married Bulma(I don't know that for sure) and had a son named Trunks. Like Goten, Trunks became a Super Saiyan at a very young age.He also helped a lot during the battle with Majin Buu.