Kuja's origin

How did Squaresoft made Kuja as we know him now?

Looks
Kuja's based on 2 characters of Malice Mizer, Mana and Kozi. If you take a look at the picture below, you can see the resemblance with the regular Kuja at the lower left, and the resemblance with Trance Kuja on the lower right!
[Malice Mizer]

Name
The meaning of Kuja's name:

Kuja is actually the name of a Hindu God and means 'Son of Earth'. In Hinduism and some astrological teaching he is known as the equivalent of the planet Mars, wich is symbolic to Terra. Mars also represents the God of Wars, wich leads back to Kuja having started wars on Gaia.
[Picture of the Hindu God "Kuja"]

More to come!