DISCLAIMER; Heir to the Empire is my main verse, but most threads will be in Knight of Ren verse unless specified. 

( In  v: heir to the empire  (Main)

Born as the only son of both Empress Revan and Emperor Valkorion, he was given a very lofty life. He knew he had step brother’s and sisters from his father’s past, but he was named as Heir to the Eternal Throne none the less.

By the time he was of age, he was already wanting out of the Empire, he wanted to be ‘free’ and more or less commit his own actions. 

That being stated, in the dead of night, Kader left the Eternal Empire with out another word, and ended up stumbling across the Knights of Ren before joining them.

 ( In v: knight of ren )

It is unknown for when Kader was born, some say it was during the days of the Empire, and some say it was during earily years of the New Republic. 

Whatever the case, he was born to Revan, and Darth Xylek. From early on, Kader knew that there was no room for mistakes in his training ~ Xylek ended up making sure that Kader knew just the consequences of his actions when he did fail.

That being stated, Kader has burns all the way up and down his arms from his Father’s harsh training exercises. It wasn’t long after that Kader’s training started when the idea of ‘killing all the Jedi’ ended up being drilled into his head by his father, Xylek.

The simple idea of failure was not an option, killing the Jedi was the top priority unless they proved to be of use, and that on itself was contradictory. That alone was something Kader always hated and the moment that he got the approval to join the Knights of Ren officially? He vowed that he wouldn’t be hurt by his father or anyone ever again.