Funny you should mention that. Just today I sent a message like that to the author of Harry Potter and the Methods of Rationality, which many people (including myself) really seem to like. Now that you mention it, I may have to spend more time on fanfiction.net. Authors must own the copyright on their work so they would have to create something original, but that shouldn't be a problem for such creative types.

Yes, authors can use pseudonyms, initials, etc. for their pen name.