Well, a very common theme is the exploration of power. In criminal Batfam fanfic, the power dynamics within the family change when they are involved in criminal - related situations. For example, who has the authority to make decisions when the family is on the wrong side of the law? Also, redemption is often a theme. Characters who have strayed into criminal behavior may seek to redeem themselves. And secrecy is another key theme. Keeping secrets from each other can be both a cause and a consequence of getting involved in criminal activities in these stories.
One popular batfam fanfic could be 'Family Dynamics'. It explores the complex relationships within the Bat - family in a really interesting way. The characters are well - written and it delves deep into their emotions.
A possible plot could be Nightwing getting betrayed by a close friend or ally. Maybe they were framed for something they didn't do, and this led to their heartbreak. For example, if a fellow hero believed false rumors about Nightwing and turned against him, it would shatter his trust and break his heart.
One possible fanfic could involve a battle against a powerful villain. Nightwing might get injured while trying to protect Gotham. Batman then has to step in not only to defeat the villain but also to take care of Nightwing. He could use his advanced medical knowledge and resources in the Batcave to nurse Nightwing back to health.
It could be his arch - enemy. For instance, the Joker might play a cruel trick on Nightwing that makes him lose someone he cares about deeply, thus causing his heartbreak.
A really popular 'batfam crack fanfic' is 'The Batfamily's Fashion Fiasco'. It's about a gala where their costumes get all mixed up. Bruce ends up in Dick's old Robin suit, and there are a lot of comical reactions from the other characters. Another interesting one is 'Batfam's Day at the Amusement Park' where their superhero instincts cause all kinds of trouble while they're just trying to have fun.
The unexpectedness of it all. We are used to seeing them in action - fighting crime, using their gadgets. But when a sneeze is added to the mix, it completely changes the tone of the story. It can lead to all kinds of new and interesting plotlines, like how they manage to keep their identities secret while sneezing in public or how they deal with the physical discomfort during a mission.
One possible fanfic could be that on Tim's off day, he decides to visit his favorite coffee shop in Gotham that he rarely gets to go to when he's on patrol duty. He sits there, reading a book, just enjoying the normalcy for a change. He might even meet an old friend from school who he hasn't seen in a while and they catch up on all the things that have been going on in their lives outside of the Bat - family chaos.