It must be hard to be the younger brother.
I know only a very little about occupying this position; the younger. I was a younger sister - but I had a younger brother too which meant that I almost literally got lost amid the oldest child and the boy child who also happened to be the baby. Despite that I was virtually invisible between my siblings and life was sometimes, painful and lonely, I am still willing to bet that life must be especially difficult if you happen to be the younger brother of a boy with Asperger's - or any form of Autism.
There are so many special rules for a child with Asperger's. How is a toddler or small child without Asperger's supposed to tell which are for the sibling and which are for him? In addition, not all children with Autism Spectrum Disorder's require the same rules. In a house where Autism lives all rules are child-specific. This is very different from what both brothers will discover for themselves in the real world.
As a parents, we know to well that constructing and consistently enforcing rules is difficult. Finding the stamina to enforce one set is hard - let alone two. Two is takes a mind-numbing amount of concentration and is completely exhausting. Because there are multiple sets of rules there are at least two sets of expectations; one for the child with Asperger's and one for the child without. The only condition that binds both is a moral foundation to do what's best, kindest, and thoughtful, to behave well and respectfully. As adults most of us struggle with identifying firm, stable moral ground. As kids, the fact that we expect them to grapple, learn and apply these guidelines borders on insanity.
As a society we believe we have learned what or how much to expect and in turn demand two sets of behavioral expectations as opposed to one moral expectation where children with Asperger's interact with others who are not affected. As educator's we cope with two sets of expectations and attempt to make both simultaneously saleable yet mutually exclusive and independent. These parameters are practically and widely necessary and at the same time they are socially cruel at the smallest level. Yet, we expect that the youngest among us, the younger siblings, those with the least experience, or with the fewest behavioral tools and least developed intellect should learn, understand, support and actively participate in this required and duplicitous system of behaviors. If the child without Asperger's happens to be the younger, it must be like trying to separate the seas. Trying to grasp that there are two sets of rules at the tender age of two or three and be mindful that this situation exists not because of parental preference, but out of necessity for the older child's handicap is ridiculous. At such a young age these very small children must accept that the rules for them are different, less lenient, more demanding and it's not because they are not the older (favorite) child.

I had a younger brother. However, I am not a boy so my relationship with my brother was completely different than that between my sons. Most important, the fact that we were different genders made most competition irrelevant. For the most part we got along. We could talk or play or at least pretend that we shared some common interests because we could communicate. What it we couldn't? Worse, what if we were talking and communicating - at least technically - but we had no idea what the other was thinking or didn't really care very much? What if we didn't understand that we should be interested in normal play? What if we had a younger brother who looked up to us who was constantly shut out through no fault of amyone's and that small boy was simply too young to understand why?

Can you image how all the appearances of privilege and preference that naturally and always accompany the role of 'oldest' are magnified when the oldest has clear and definable needs for another set of special rules? Can you imagine trying to identify those rules and properly compartmentalize them while you are in the midst of attempting to grow up and understand social order and the world in general yourself?
It must be very hard to be the younger brother of someone with Asperger's. The rest of the playing field is even enough - but for the brother of an Aspergian, that same playing field must seem at times a very lonely place.
It's true. Not only the child with Asperger's is affected when this disorder appears. We all are, in ways that we cannot possibly understand yet must somehow learn to cope with.