Perhaps he's in a creative rut. When someone tells the same story over and over, it might suggest that they're having trouble coming up with new material. It could also be that this particular story has some personal significance to him and he likes to share it often. For example, it could be related to a life - changing event or a very memorable experience that he wants others to know about.
The theme of justice is also very common. Both Sherlock Holmes and Batman are dedicated to bringing criminals to justice. In fanfiction, they often team up or compete in the pursuit of this goal. They might have different ideas about what justice means exactly, but they both strive to make their respective worlds a better place by stopping the bad guys.
Maybe there's a mystery that spans both London and Gotham. A villain is using a new kind of technology or drug that was first experimented with in London and is now being exploited in Gotham. Sherlock Holmes, having heard about Batman's reputation for dealing with such matters, travels to Gotham. They meet and initially clash due to their different methods. But as they start to share information, they realize that the villain is someone they both have a history with in some way. They then combine their efforts, Holmes with his mind and Batman with his gadgets and physical prowess, to stop the villain.
The Riddler could be a great main antagonist. He loves to create complex puzzles and mysteries, which would be right up Sherlock Holmes' alley. And of course, Batman has had his run - ins with the Riddler in Gotham. Holmes' deductive skills and Batman's combat and detective skills would be put to the test trying to outwit the Riddler's convoluted plans.
One great Sherlock Holmes Batman fanfiction is 'The Detective's Alliance'. It combines the deductive skills of Sherlock and the dark vigilance of Batman in a really engaging way. The story has them team up to solve a mystery that spans across Gotham and Victorian London. Another one is 'Holmes in Gotham' which focuses on how Sherlock would adapt to the chaos and crime of Gotham City while also interacting with Batman and his rogues gallery.
Pete Enns in this context is presumably the main figure behind the act of 'telling Gods story'. He could be someone who has dedicated his life to understanding religious concepts related to God. His role might be to bridge the gap between traditional religious teachings and modern audiences. He may use his own experiences, research, and understanding to make the story of God more relatable and understandable, whether it's through writing, speaking, or other forms of communication.
It's hard to say for sure. Some fans might be really into it as it offers a different way to experience Pete Townshend's Lifehouse concept. But others may prefer his music or other traditional forms of his work.