I'm not sure who specifically 'Hugh Marlow' is in the context of science fiction. There could be many relatively unknown or emerging authors, characters, or contributors with this name in the vast field of science fiction.
It's fairly common. Fans often look for more content related to their favorite shows. Since 'Attack on Titan' has a large and passionate fan base, there are a lot of fanfics available. 'Aot' fans might watch (read) these fanfics to explore different scenarios that the official story didn't cover. For example, they might want to see how a certain character would react in a different situation or what would happen if a major plot event had a different outcome.
Well, without having read the book, it could be about a club in Marlow that is centered around solving murders. Maybe there are unique characters in this club, each with their own skills and motives. They might face a particularly difficult murder to solve, and the story could be about their journey in uncovering the truth, dealing with suspects, and collecting evidence.
There could be various fanfictions. Maybe some that focus on alternative endings, like ones where certain characters survive who didn't in the original. For example, a fanfiction where Erwin survives and leads the Scouts in a different way.
Marlow often uses vivid descriptions and personal anecdotes to weave the inner story. His tone and style make it engaging and immersive for the listener.
It could mean that a person who is a fan of 'Attack on Titan' (AOT) is reading or watching fan - created fictional works related to AOT. Maybe they are interested in seeing different interpretations or storylines that fans have come up with.
One way is to check on popular fanfiction websites. Look for ones with high ratings and a lot of reviews. For example, Archive of Our Own (AO3) has a large collection of AOT fanfictions. You can search for the most popular ones there.