Re: true names
Now, I happen to believe that there are such things as true names. That if one so happened to know the true name of a demon that was not incarnated, one could try to summon and control it through that name. Whether or not one would be successful would be another matter altogether. For inasmuch as a true name will touch on the very core of who the demon is, the knowledge is less than useful if you don't know what you have or how to use it. And I am not entirely sure that we would recognize a true name as such if it wasn't marked somehow as being one.
There are birth names, legal names, the names we use and nick names we are given along the way. None of these are true names for all that they can identify someone. But these are the types of names we use most when it comes to others and ourselves. All of these can be shared by two different people that have no connections one to another. We would be more inclined to think that true names, on the other hand. are unique. But to go back to the names we know, how much any of them mean depends on how well you know the person being referenced. And in some cases the setting in which one name or another might be used.
Names in usage are tied to selves or personas. And while someone who knows you very well can convey that knowledge by tone in connection to the names we use, that is the closest thing we can think of to describe what it might feel like to hear someone use your true name. I know this is not a comprehensive answer that covers everything, but it is the best one I have at the moment.