Back in the '70s Isaac Asimov, editing a collection of the year's Hugo winners or at least some collection of science fiction, recounted a story that I can't find on the internet but I'll quote it as best I can:
Back in 196?, at one of the sci-fi cons in <
city>, there was a young fan who seemed memorable. He was short, had big glasses, and was very serious; he ran around approaching authors, asking questions and taking notes. Sci-fi authors are easily flattered, as you might guess by listening to me, and many of them gave him lots of hints. We had no idea, of course, that this one was going to grow up to The Harlan Ellison.
A few years ago a weird sense of déja vu came to the con in <
city>; there was a young person, big glasses, very serious, taking notes. We all looked at each other and said "It's him!"
And one of us, whose name I won't mention except to say that his initials were Robert Silverberg, said "Let's kill him now".