The dark side offers power for power's sake. You must crave it. Covet it. You must seek power above all else, with no reservation or hesitation.
Darth Raiva, the brother of Revan, and the Lord of Anger, was born in the year 3,936 BBY in the Outer Rim. He discovered the Force at a young age, and followed his brother Revan to war. Upon Malak's defeat and Revan turning to the light side, Raiva took the throne himself.
In time as the ruler of the Sith, Darth Sion, Darth Traya, and Darth Nihilus faced off for power. It led to Traya's downfall and Sion and Nihilus were eventually defeated by the Jedi Exile. She eventually faced Raiva and was defeated.
While most details on Raiva's childhood were unknown, he was born somewhere during the Outer Rim Sieges. When he was a child, his parents, Revan, and him went to Korriban to pick up shipment. Raiva sneaked out of the ship and they took off not knowing he was missing.
While Raiva was Force-sensitive, it was mainly focused on the ways of the Sith. At a young age he would be apprenticed by Jorak Uln.