Autism developed into narcissism?

Hello all, I am new here and am trying to get a serious opinion.

My son is 22 years old, nearly 23 now. Ever since he was very young, I knew he was autistic. He had no imagination when a toy was put in front of him unlike his brother or sister and he slept 4 hours a night. When he reached primary school, they recognised that he had severe learning difficulties. I didn't get him diagnosed at the time because I thought he was under good care with the school. When secondary school came about, everything was good until year 9. He gained quite a bit of weight (eventually reaching 19 stone at 18) and he started to say things to students so black and white that were highly rude however true because he saw it as just that. It ended up with him leaving school, becoming a recluse in his room and learning how to use computers. He became extremely advanced very quickly however used this in a criminal way and started hacking ect. I tried to divert him from this by getting him into college in IT. He attended and enjoyed it and went on to study for the next 4 years. During that time, the hacking calmed down, he made some good friends ect and had a normal education like his brother and sister. He would still have his traits (forgot to mention these) such as very poor hygiene, repetitive playing of music such as 1 song for a whole week and not being able to understand sarcasm ect. This however all changed over time and now I am highly confused. All of a sudden it was like the reverse. He put himself on a severe diet eating only 500 calories a day, in which he lost 7 stone in a year. He went from anti social to always going out and when he would come back he would be him self again which was playing xbox, being on the computer and watching documentries. A couple years pass, and all of a sudden it's now like seeing a narcistic. He is highly manipulative, he is highly analytical and is able to manipulate anyone he wants. He is highly vain, will always look in the mirror and thinks he is gods gift. He is the complete opposite in confidence now going from anti social and not speaking a word to walking in the room and right away recognising the leader type role. He is highly good at now debating with people and pointing out there flaws within there logic or sentences and wording it to make them feel dumb. He has no value for money in the slightest and wouldn't think twice about dropping 100 pounds on the floor. However he is highly caring towards certain indivduals and it's like the whole world around him doesn't exisit. I have no idea what the heck I am dealing with. His father also possessed potential sociopathic behaviour.

I must also state that his intelligence level has gone from kind of below average to genius pretty much. I honestly don't understand how this is even possible. Also he was officially diagnosed as having Autism and ADHD impulsive as he is addicted to gambling so this is linked with the finance bit and I have been made his financial apointee for good reasons.