I learned about Esperanto from the novel series the Stainless Steal Rat. I was really disappointed with the audio books though, because I always pictured him a young guy, maybe a bit pompous or silly. But certainly not an old gruff grouchy guy. :(
I thought it was just awesome when 10 years later I found out Esperanto was real!
I thought it was neat that Esperanto was used in the books. I first learned of it in about 1980 from a book belonging to a friend's father, who was in the military. It was called 'Esperanto: The Aggressor Language", because it was used by the US Army in their training games.
Believe it or not, I first heard about Esperanto in a Man From UNCLE book (The Monster Wheel Affair), where the bad guys used Esperanto so no one would know what country they came from.
I thought it was just awesome when 10 years later I found out Esperanto was real!