emo-beth
The legend is that long ago there was one orb that contained all the powers of magic. One day someone wanted those powers form himself. The guardian of the orb swore to protect it. The guardian knowing he couldn't win broke the orb in four breaking them into light, darkness, fire, and water. The four shards of the orb where sent into the soul chain and put into four human souls. The children would eventually meet and stop the people who the guardian tried to stop all those years ago.
(the story starts 20 years later, Ps: all of them are the same age)