The plot is crucial. It could be an alternate universe story where Tim has different circumstances, like being a part of a different superhero team. Or it could be a story that delves deep into his past traumas and how he copes with them. A good fanfiction also has engaging dialogue. When Tim is interacting with other characters, the conversations should feel natural and in - character. For instance, his banter with Dick Grayson should reflect their brotherly relationship.
Another aspect that makes a good Tim Drake fanfiction is the world - building. If it's set in the DC Universe, it should stay true to the overall lore while adding its own unique elements. For example, if it's a story about Tim in Gotham, the description of the city and its seedy underbelly should be vivid. And of course, the writing style should be engaging. If the prose is dull or hard to follow, it won't be a great fanfic even if the concept is interesting.
A good Tim Drake fanfiction often has a well - developed character for Tim. It should capture his intelligence, his detective skills, and his complex relationship with the Batman family. For example, a story that shows him solving a difficult mystery using his unique approach would be great. Also, a good fanfic might explore his growth as a character, like how he overcomes his insecurities.