Blues, all of the varieties, or simple recessive. If you are working with the same blue gene, (aka, english vs russian) then you have a chance of getting more blues when you cross two blue parents.
If you cross the Siamese with any of the blue females, if he is not het for their blue gene, then all the babies will be black or agouti, het for blue, het for siamese.
Siamese is also recessive, need two copies, preferably on a black (not agouti) color to see it at it's best.
There are a lot of genetics you have to work with, have fun with it.
cheers,