As with real spiritual demonic possession, those metaphorical demons can also lay dormant and then resurface and cause a lot of problems...and...they tend to resurface when we are in a weakened state...they love for you to be under the influence of something that alters who you really are...that's when they have a heyday. They love to inhabit drug infested places.
So, what to do? Face them. Takes courage, but they will never leave unless we face them. They can be very tenacious; very strong, so getting rid of them is not easy. We need to be just as tenacious in our desire to have them out of our life. When demons are cast out, they don't just disappear into thin air...they will find someplace else to occupy. But they are far less likely to come back if we don't make ourselves "hospitable" to them.