What would happen if the second personality took over the first personality? Would his body change? Would it cause harm to the human body?

This kind of situation doesn't exist in real life, but it often appears in novels and fictional stories. If the second personality occupied the first personality's body, the following would happen: Physical changes: The second personality may have a stronger body than the first personality because they occupy more muscle and bone tissue. However, this change might not necessarily cause harm to the human body, depending on the physical condition of the second personality and the first personality, as well as their ability to control their bodies. 2. Mental changes: The second personality may have more mental energy and richer emotional experiences because they have already experienced the same life experiences as the first personality. However, this change may cause the first personality to feel uneasy and anxious because they feel that they have lost control. 3. Relationship changes: The second personality may have an unusual relationship with the first personality because the two personalities have experienced the same life experience. They may form an emotional bond that is mutually dependent or mutually exclusive. This kind of situation doesn't exist in real life, but it often appears in novels and fictional stories. If you want to know more about this situation, it is recommended to read related novels or consult professionals.