Nero was just a poor boy who wanted to play the fiddle. Are you sure Caligula isn't a better comparison? He's the one who constantly tried to own the ̶l̶i̶b̶s̶ senate. That's what the whole deal with the horse was about.

I'm reading Iain McGhilchrist's The Master and his Emissary. There's a bit about right brain damage correlating (fact?) to lacking empathy.

    Patients with right frontal deficits, but not left frontal deficits, suffer a change of personality whereby they become incapable of empathy.

Perhaps try reading more history about Nero.