The detail of what you know of them and what they like might be the clue to help get rid of the dreams; I would not think about them, change what you are thinking about when it strays to them and remind yourself they are only thoughts and hallucinations. Or, the opposite, realize you enjoy thinking about it and allow yourself to do so since they are just like daydreams; no one is getting hurt and no one but you knows what you are thinking about.