I have just begun a new serial involving a mentally ill antagonist. I had seven false starts, and weeks of research into her particular form of illness. I also chose to leave the door open to her not actually being delusional but still ill. It is the possibility of misdiagnosis that I feel will give more drama to the situation. The protagonist will have a lot to reconcile for himself, as well as suffer the consequences of his own fallacies. In my research I found so much variation in the disorder, that it has made much of my time fruitless. Of the twelve case studies I found, it appeared more like a catchall disorder for twelve very different people. What references do you prefer for medical insight for characters? I ended with a bit of an amalgamation of all twelve, as well as a childhood friend who was later diagnosed after a major break.