My son is 17 and is around the middle of the autism spectrum. He talks, but his vocabulary and behavior reflect a small child rather than an older teen. He has low verbal IQ but high spatial reasoning and mathematical ability. This means he has difficulty with communication and anything to do with understanding people, but he does well with certain types of problem solving. He is very sensitive to touch and sound. For him, this means, he likes to dress to cover himself head to toe, even when it is hot, to reduce what he feels from outside stimuli. He also often wears noise-cancelling headphones to block out normal noise since everything seems loud to him. As such, he tends to speak very loudly because he is trying to match the volume he "hears". We've never gotten him to use an "indoor voice" or realize he is louder than everyone else. He currently lives in a group home for boys with behavioral problems. All 3 boys in the home at this time have autism. I have heard that 1/3 autistic people have issues with aggression.
I once read a book with an autistic character which was very poorly written. I do not think the author had ever dealt with children, much less an autistic one. He took some random stereotypes and threw them together in a way that made no sense to describe any real person.
For any person, you need to understand "why" they act the way they do, not just have a list of common behaviors. Autism can manifest in many different ways. They say if you have met an autistic person, you have met one autistic person. The list of behaviors is rather generic, but any given person's issues and responses to situations can be very specific. I can give some examples of my son's behaviors which classically fit an autism description, but that doesn't mean other autistic people are just like this.
I will tell a story of an incident with him from his own perspective. Shortly after he arrived at the group home, some staff took the boys into the backyard to play basketball. Now, he does not like this chaos and complained about the "aggressive behavior". People were running around, jostling each other, and throwing things. He tried to move off the court to get away from it. But then it got worse. One of the staff threw the ball at him and it hit him. This was painful, but instead of asking if he was ok, the staff member made fun of him by smiling and saying, "You can't catch!". To make matters even worse, the staff threw the ball at him again! Now, my son wasn't going to deal with that. He was new here and not going to put up with bullying. So he went up to this staff member and punched him to show him he wasn't going to take this kind of abuse.
Now, this story could be read much differently from another point of view. Staff were engaging the boys in a social activity to encourage exercise and learn to work together. But I told the story from my son's perspective to explain why in *his* mind, he was responding in kind to an aggressive act against him. Thus, autism with behavioral problems. (Incidentally, for my son the best way to deal with this is just to not try to engage him in sports at all. He can exercise through walking in the park and swinging on the swings.)
When he gets stressed, he does best being left alone with legos or Minecraft, both "building" types of activities which are fixations for him. He also likes being wrapped in a heavy blanket for comfort, or swinging on swings. Many autistic people have repetitive or sensory-oriented behaviors which calm them. Even though my son can talk, when he is feeling strong emotions, such as very excited or very angry, he reverts to non-verbal sounds such as squeals or growls.
Another aspect of dealing with autism is responses of others. This gets tricky because not everyone is particularly compassionate or understanding when behaviors arise. Over the years, I have heard people say autism is an excuse for lack of discipline, a good spanking would resolve that (but for someone who finds even light touch uncomfortable, spanking is downright abusive), and in his teen years we have had people call the police when he acts out. This is understandable because by now he's a big guy and hard to manage. But he isn't someone who will "learn a lesson" by going to jail - where triggers would abound even more. Thus, he ended up in a group home where his behaviors can be greatly prevented or managed by controlling the environment.
Still, this is just one person's story. If you are going to invent a person who fits the generic autistic symptoms, make the behaviors specific for that person. This is where it will help to meet - even online - as many people as you can to get a realistic idea of a day in the life of autism.
