Black Pastels and Cinnamons do the same thing differently.
You can make Pewters with your Pastel to a Black Pastel or Cinnamon, You can make more of the basic Co-dom (BP or Cinny) if you plug it in to normals, and you can work the long haul by plugging her into your Het Pied project and make Cinny or BP poss het Pieds, eventually breeding to get BP Pieds or Cinny Pieds.
If you get a pair, you can make Super Cinnies or Super Black Pastels, which are solid grey or black snakes!!
I LOVE Black Pastels and Cinnies. They can do so much!!!