The other character that inspired Dave Dreamer is Uramichi Oniisan's Iketeru Daga.

Iketeru is arguably the most put together of the broken adults of Uramichi Oniisan but not by his own admission, his crazy talent for singing and ability to learn something on just mere instructions alone, means he has a better time of things than most but there are moments where he can't function and his inability to read the room can make him extremely vulnerable, he has a meltdown over not being able to cut paper and his child like innocence makes him a giggling school girl at the mere thought of a dirty joke, he can't even win a proper argument without completely forgetting why it even happened.
The term for this is Savantism and that is pretty much Iketeru in a nutshell.