I wonder what kind of प्रशंसक Fiction to write...

Well, if you're a new प्रशंसक fiction author, I'd suggest picking the स्रोत material you're most familiar with, and लेखन about it in canon style. It's simpler than alternate character interpretations, OCs, AUs, and anything else deviating (radically या otherwise) from the original source. It's also likely to garner less hate, even if it isn't incredibly original. Just don't rip off an existing episode.