Hi,
I am currently struggling over the school holidays with DS1 9 who is autistic and adhd with sensory processing issues and his 5 year old brother who is neurotypical. DS1 wants to shut himself in his own world and is very much stimulated by researching his obsessions and making animations on the computer. When he is doing this he 'stims ' a lot and generally will not engage with us unless he wants food or drink. He hates going out. I have had to force him out a few times like to go on a staycation for a week and to a few soft plays so that his brother can see other children. He coped ok but it is difficult for me because he becomes clingy and anxious and doesn't cope with the noisy, hectic and social environments that his 5 year old brother needs.
That said, I am proud of SN DS1 for coping with it for his brothers sake and I do acknowledge this and tell him this. However when we go home and when we have our quiet days at home DS2 gets very bored and upset and doesn't understand why DS1 never plays with him. He adores his older brother and even adapts to his interests and really tries to get him to like him
it breaks my heart because often if DS2 badgers DS1 too much while he is in his own world on the computer, DS1 will tease him and impersonate him which makes DS2 cry.. DS1 can say mean things without remorse too like "I wish DS2 was in a different family not here" in front of him. I play with DS2 and so does his daddy but he says he wants to play with other kids. I talk to him about making friends at school but he says that he likes his big brother far more than the boys at school because they aren't into what DS1 and 2 are into 
I am a SAHP/carer and neither DS1 or 2 are happy with going to a holiday camp or other activities without me. In fact both get rather upset if I even suggest it.