Yellows, Butterscotches and Oranges are all compatible. I believe that selective breeding of the Hypos have led ur to some different collors. If you started with a Orange Hypo and continued to breed the yellower(is that a word) offspring together, you would end up with Yellow babies, as with the Oranges. Continue breeding the brightest Orange animals with simlar animals and you end up with an Oranger(still don't know if that is a word) animal. I have not seen any Hypos BROWN-OUT with age. In my experience they seem to get more of a bleached-out look as they age. I do not own a Pastel Hypo, so I cn not really comment on how they age. Hope that helped some.