Read any kind of magic or fantasy literature and you'll soon find out that names have power. Knowing a person's (or being's or creature's or whatever's) true name gives you dominion over them. Think Rumpelstiltskin. Think Beetlejuice.
On the other hand, if you don't know a thing's true name you don't really want to make it angry either. (Think Incredible Hulk, or any other character who chooses to keep their true identity secret. Would you really like to piss off Clark Kent or Peter Parker?)
Lots of writers choose to use pen names, sometimes because their own names don't suit their genre, sometimes to hide their true identities (just like Superman). George Eliot, Currer, Ellis and Acton Bell, J.K. Rowling, all chose to hide their gender behind their noms-de-plume.
For the purposes of blogging, I'm AJ. For the purposes of my profession I'm known by my given name. I am never known as Annie. Unless you want to make me angry. And you wouldn't like me when I'm angry.
