Dicks parents died and Dick wanted Tony's blood, so Deathstroke helped him get it. They worked together, taking any jobs that came their way until being hired by the light when Dick joined the young light league

Wally never really liked his parents and ran into the streets where he became a small thief, he was captured by the Brain as a test subject but proved to be worth more. The Brain gave him superspeed and took him on as a apprentice

Artemis left with her sister joining, the league of shadows and slowly made her way through the ranks, surpassing her sister and becoming a right hand to Talia- who nominated her to be on the young light league

Megan was separated from her uncle after she snuck away to earth on his ship and he tried to make her return to Mars, she ran to the desert and met Queen Bee she was interested with Bee's own mind control powers and they teamed up to take over all of Byala

Conner was never rescued from Cadmus and mindlessly follows orders

Kaldur was raised by his fathers side as an outcast of Atlantis and is completely loyal to his father