This person does not like his birth name; if you call him by it, he will either correct you or ignore you. This could be for a number of reasons. He might feel that you are assuming too much familiarity with him. He might find his real name embarrassing (though his alias is not always much better). He could want to reinvent himself. Or it might be that no one calls him by that name besides his parents. Could be related to Embarrassing First Name, but that is more about an annoyance. This one is more prideful and dramatic. For obvious reasons, this is very common with Transsexual characters.