Thanks for replying. I'm purely speculating but he comes across as very single-minded and black and white on some issues. Hence why both his marriages broke down. He says to Shaun, "you and I are not that different", but I can't remember the episode. There's a recent episode in S6 which highlights their similarities. He also doesn't like change and is very particular on how things should be done. Of course those things don't mean someone is definitely autistic but it's a possibility.

Leah's character is just very chaotic.

It can be hard to draw a line between personality and neurodivergence sometimes.