I had noticed the OCD and realised it had steadily escalated to an unbearable level. I read an amazing book on dealing with people with OCD. (I am not saying all people with OCD are narcissistic but I do wonder if all narcissistic people struggle with OCD. I have my own theories on this. I believe he did his level best to cause OCD in those around him.) The book, to my surprise, had not recommended a sympathetic response. My personal experience has led me to believe that the number and type of OCD behaviours, is a good barometer of the state of mind of the narcissistic person. I have my own theories on this.
My observations have led me to believe that toxic people tend to have their own particular way of announcing that they have arrived and that they are in charge now. I believe they probably have similar techniques upon their departure, attempting to ensure their presence is still felt, whether they are present or not. It does not hurt to be at least aware of these routines.