One reason is Arthur's complex character. He's a tortured soul with a violent past but also a sense of loyalty. Fanfics can explore his psyche in ways the show might not fully. For example, they can show his inner thoughts during crucial events.
Well, 'Arthur Shelby's Untold Story' is quite interesting. It focuses on Arthur's past and how certain events shaped him into the man he is in the series. Also, 'In the Shadow of Arthur Shelby' gives a unique perspective on his relationships within the Shelby clan and with other characters.
I don't really know who Shelby Day is in this context as I haven't read the book. But I assume Shelby Day is the author of the novel who has created this story about the lost girl.
Some cable TV channels that focus on automotive or documentary programming might air 'Shelby American: The Carroll Shelby Story'. Check your local listings. Also, some specialized online documentary websites could have it available for viewing.
Shelby is the protagonist in 'A Dog's Way Home Book Shelby's Story'. Shelby is a dog that has to find its way back home. Throughout the story, we follow Shelby's experiences, its encounters with different things and beings on its path home.
Will Shelby could be a source of inspiration in Glee fanfiction. His passion for music and teaching can be a driving force for other characters to pursue their dreams.
The character of Thomas Shelby from 'Peaky Blinders' is fictional. However, the show is set in a real historical context, with elements like the post - World War I Birmingham, the gang culture, and the social and political climate of the time being based on real historical research. But Thomas Shelby himself is a creation for the purposes of the TV series.