Hello beaneroconnor,

Having a severe mental illness does not mean that someone is going to be violent, infact most are a danger to themselves not others. That said, he needs treatment so try to persuade him to see a doctor for his own health. If he will not go then you can contact his doctor or mental health services with your concerns. They may not be able to do anything while he has capacity to make his own decisions. If he becomes violent then you need to think of your own safety and call the police, this may help him in the long run to get the treatment he needs.