I think that your brother may be suffering from the early stages of psychosis
(if this is a recent development), and needs the urgent intervention of a psychiatrist
. He will tend to make-up situations and then feel compelled to believe or assume them to be real. He may be gradually getting disconnected from reality. I, myself, am presuming this from the limited information you have given. Ideally you should take him to a psychiatrist soon for an assessment and some medical intervention as the doctor feels fit. Along with the medical advice he will need to seek parallel therapy, so seek the help of a counselor is advised too. The combination of medicine and counseling will help him stabilize and lead a normal life. Otherwise his condition may deteriorate and it may become very difficult to alleviate later on.