Fun idea I had a few hours ago. Probably I'm not the first one to come up with this, but whatever.
It goes more or less like this:

- The Prince and the Beast-
A long time ago a princedom was being attacked by barbarians raiders.
The Prince knew his princedom would be taken by the barbarians, so he summoned a witch called Faere to the castle.
With the witch's help the Prince contacted a demon and made a deal with it.
If the demon gave power to the Prince beat his enemies, he would work for the demon as long as he lived.
The demon transformed the Prince in a nightmarish Beast.
With his new powers the Prince easily vanquished his enemies, however the demon asked the Beast to give him one soul every year as payment.

-The Beauty and the Beast-
For ten years the Beast ruled his princedom hiding inside his castle, training himself to use his new body.
For ten years the Beast kidnapped young girls and convinced them to give their soul to the demon that gave him his new form.
Meanwhile outside the castle, a knight named Gastus became known as a hero to the people of the princedom.
Gastus fought valiantly against the barbarians, while the Prince locked himself inside the castle.
Gastus means to marry a very beautiful lady of the village, but before he could do so, the Prince kidnaps the girl.
For months Gastus search for the girl's whereabouts.
Unknown to the hero, the girl and the Beast fell in love with each other.
The Beast refuses to give her soul to the demon.
Gastus found out that the kidnapper was the Prince, so he goes to the castle to rescue his lady.

-The Knight and the Beast-
[I'm too lazy to keep typing]
[I'll probably make a flash book with this story]