Short story. how to develop my character(a psychopath)?!

i need to do a short story for my gcse coursework, in my old class we were told we had to do one on war which i know nothing about, in my new class we have to re-write it on whatever we want, i want to do quite a complex but slightly distrubing thing lol, basically about this boy whos dad was resusitated and his soul like went when he was brought back to life and he ended up hurting the rest of the family!. the kid is older and he goes back to that hospital and sees the room where his dad was brought back to life, and so anyone who enters that room he kills!. just wondering tho, how can i get into detail about this psychopathic killer, what kind of traits to do they have, how are they as a person, what would they do!? just these kind of questions lolWww@Answer-Health@Com

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