There are two factions in this world, those that believe that there should be regulation on emotion as it leads to war, suffering, and general harm to all whereas the other believes that we should be the humans that we are meant to be. With two superpowers dueling with each other over the right to their citzens' very feelings in an odd twist of fate it is a psychopath, one devoid of all emotion naturally compared to the artificial ones that government had been working to create with not much success, that seeks to bring down this whole notion that people devoid of emotion are the best kind of people. For he, himself is not one that is purely good as he has done horrible things and does not feel yet a thing after them other than the enjoyment of having done them.
He is no illegal serial killer or anything like that, he was an interrogator for the CIA in their rendition program, taking suspected terrorists off US Soil to far away lands where the Geneva Conventions on torture are not even known let alone ratified. So he should be the one whose testimony that is accepted the most as he was born psychopathic, known for being brilliant even from a young age. But also being generally despised and feared from middle school on up for the sheer fact that if you crossed him, bad things happened.
Sadly, the country of China discovered that there was a drug that could lose the processing of neurotransmitters in certain parts of the brain not too long ago and are working to use it not only on their soldiers but their general populace for the thought that it would cause peace. They also in a bold move have decided to try to use their political weight to cause other countries to do the same, with only the most extreme of them agreeing. The US began to attempt to stop this by bringing him to testify in the middle of the UN chambers to prove that psychopaths, natural ones, are not peaceful creatures as the Chinese claim. And though it does swing some of the countries to their side, China is saying he is a fluke and after the meeting sends an assassin, one of their artificial psychopaths to kill him to stop the use of him against their peaceful plans.
That is where the story would begin with a psychopath that is natural, my character and yours being an artificial one that is sent to deal with him for the sake of China's version of peace.