One of my main villains is a doctor. He's the classic mad scientist type and he's primarily a surgeon but he's knowledgeable enough that he can make chemical and biological weapons he's also good with mutation. Basically he's your average movie super villain.
He would be the fictitious kind of doctor, which is absolutely fine. If he’s smart enough to be a surgeon, he’s smart enough to learn the rest.
I know a guy who started as a doctor but then he went into cybernetics, and he's working on human-AI interface technology. I know a few scientists ( geneticists, chemists, biochemists) who went on to study medicine so have dual degrees. And then you have doctors who focus on research, they are usually specialists (like neurologists for example) who hardly ever see patients and mainly conducts studies and experiments (sadly, usually on animals or less sadly, on tissue cultures). I even know doctors who are lawyers at the same time. The combined skills can be quite unrelated, so you can really mix and match skills to suit your story.
My first degree was of course medicine, later I pursued post-graduate interests, included here my astro-chemistry at Cambridge diploma. When the letter from NASA arrived I combined all of my passions and pioneered the insertion of liquid microchips inside of the newborns' cranial areas - or the heads specifically. I like to think my own scientific achievements speak for themselves.
You could also make him an cyber-mutant-orthodontist, so he'll freak away any living been around him for certain.
Organic chemistry is a prerequisite for admission to medical school. (Or was when I went to college in the 1960s)
