How did he get the name AVI and why doesn't he tell people his real name?

Authors choose a pen name for many reasons. Sometimes, they just want a private life where people are not always calling and showing up on their doorstep. Sometimes, they like the sound of a name and use that instead of their real name. Sometimes, they use different names to write different kinds of stories so that people won't be confused and pick up a book that they think is going to be one sort of story, only to be disappointed that it is something else entirely.