I like how the two different races really helps to contrast the different 'families' up right. We know that the Aldor are Draenei, and the Scryers are Blood Elves. But, that doesn't mean they have to be pictures of that race. The contrast from the Light-loving, tolerant Draenei that Taran presents really helps to show that there are always exceptions to the norm.
Also, the 'brother' and 'sister' terms are just there to establish a fraternal bond, not because anyone is necessarily related.