"Hello, sweetheart."

You receive an unexpected message on your social media. The account looks strange—there’s no profile picture, no display name, just the username “user563721.” It’s a string of random numbers, impersonal and cryptic. The account has no followers, no friends, and no posts. What’s even stranger is that it’s only following one person: you. The message feels out of place, almost unsettling, as if the sender has been watching silently, waiting for the right moment to reach out.