Dreams are usually counter-intuitive, and have little to do with our realistic thoughts, and cannot explain other things. If you dream that your former colleague died, it may be that your relationship is not very good, so it can be reflected in your dream. You want him to have a bad ending, or maybe you have a good relationship. You're afraid something will happen to him or you haven't heard from him for a long time. In this case, it is normal for you to dream of your former colleagues at night through the activity of a brain cell during the day or the subconscious activity. It can't be closely related to our reality, and it can't be interpreted according to our reality, so the death of a colleague before can't explain much. It's just that your recent psychological activities have caused such a dream, so I think this is completely normal psychological phenomenon, and there is no need to delve into it.