Many years ago when the Old Republic was just in it's inception, there were only Jedi.

However, this was not to remain true forever. Some of the Jedi began to experiment with other manifestations of the Force and alchemy. From these Jedi rose the pratictioners of the Dark Side. These Jedi were condemned for their practices and exiled from known space for their evil ways. This may have been more of a blessing than a curse for the Dark Jedi.

After countless hyperspace jumps, the Dark Jedi happened upon a race of creatures known as the Sith. The Sith worshipped the Dark Jedi as gods for their use of the Dark Side. This began the Sith Empire.

The Dark Jedi quickly enslaved the Sith breaking them into many different classes of worker each serving one Jedi's whims and needs. Eventually the Jedi bred with the Massassi warriors making the various Sith bloodlines of today.

The Nor'Dana bloodline started in a similar way...

Of the original Jedi who were exiled, there was only one woman. Lessa Nor'Dana had always been a manipulator as a child. In school she got the grades she wanted and dated who she chose. Being selected for Jedi training due to a high Force potential was unexpected, but she learned quickly. Too quickly as old habits die hard. After seducing a more experienced Jedi she was quickly drawn to the Dark Side.

She never had a chance when they caught her. Seven Jedi and a squad of police stormed her room at the Academy. Only two of the Jedi were left when she was caught.

Her exile left her bitter and lonely yet she knew she had an interesting situation on her hands. Being the only woman, she could use this to her advantage. Carefully, she built a stronghold on one of the far moons away from Ziost, the homeworld of the Sith Empire. Hidden away from the plans of the other ambitious Sith Lords she could use her powers for her own pleasure and entertainment.

Eventually, she took a husband giving birth to a little girl. Thus began the matriarchy of the Nor'Dana bloodline.