Riku is a Hero consumed by the power of darkness.
He was a boy so desperate to go off Destiny Island he was ready to give up his friends. Then, he got consumed by darkness and kept wanting absolute power. But when he got defeated by Sora, he realised that the heart becomes stronger by protecting your friends. Then the bit of light left in him shined and manedged to push the darkness out of him.
He can still control his dark powers (KH: CoM).
And he helped Sora kill Xemnas (Mansex )
He was a boy so desperate to go off Destiny Island he was ready to give up his friends. Then, he got consumed by darkness and kept wanting absolute power. But when he got defeated by Sora, he realised that the heart becomes stronger by protecting your friends. Then the bit of light left in him shined and manedged to push the darkness out of him.
He can still control his dark powers (KH: CoM).
And he helped Sora kill Xemnas (Mansex )