Not sure whether this is actually not possible or if I'm just too dense to figure it out, but...
...I know a user who is in the process of writing their very first story. So, I'd like to follow them to get notified once they post it. And, even though I know their username, I don't know how to even find them on this site. The author list doesn't seem to simply list users, but only pen names under which stories have been posted.
For that matter, I can't even figure out how to message someone if they don't have any stories posted, like when I read a forum post from them and would like to start a less public conversation.