Am finding it hard making some meaning out of your narration, but I think I can come up with a direct answer using only the question. Allow me begin by seperately explaining the meaning of paranoia and schizophrenia before drawing a conclusion.
Schizophrenia is a mental disorder usually characterized under abnormal social behavior and also the failure to understand reality. A person suffering from schizophrenia will show symptoms like confused thinking, false beliefs, lack of motivation and sometimes, hearing of voices.
All these explained above simply means that a person who has schizophrenia is suffering from a complicated mental disorder. Such persons will usually have reduced social engagement due to their inability to think, behave and act normally, and most importantly, tell what's real or not.
Paranoia is defined as an instinct or process of thought believed to be heavily influenced by a person's mental state, which often leads to the point of delusion and irrationality. Paranoid thinking usually involves beliefs of false imminent threat to oneself. This means that persons in such state will always have negative thoughts on people's behavior towards them. They'll lack the ability to trust people thinking everyone around them wants to harm them. Persons who have chronic paranoid thinking will likely act violently most of the time.
Now, imagine persons suffering from both paranoia and schizophrenia. Going back to your question - how on earth can a normal person reason and understand with someone who has paranoid schizophrenia? I mean, being paranoid alone is hard to handle, topping it up with schizophrenia makes it almost impossible to handle. So, as long as you have a mental state which is classified as rational or normal, there's absolutely no way you could ever understand the actions of people suffering from paranoid schizophrenia. And besides, I highly doubt that they too understand their own actions.