One possible theme could be redemption. If there is a character who has 'fallen', they might be seeking redemption. Another theme could be justice. DCI Matilda Darke is likely to be striving for justice in the story.
Possible themes include the fall from grace. This could be about a character who has lost their standing in society or within themselves. Also, the theme of truth - Matilda Darke's search for the truth about the 'fallen' situation. It could also touch on themes of morality, as she has to make decisions that test her own moral compass while dealing with the case related to the 'fallen'.
I haven't actually read this short story in detail. But generally, it might be about a case that DCI Matilda Darke is handling. The 'fallen' could refer to a victim, a suspect, or perhaps something symbolic like the fall of an institution or a person's moral fall.
Another theme might be isolation. Matilda could be alone in the city, and the presence of the ghost could heighten her sense of isolation. Also, it could touch on the theme of the past haunting the present. Maybe there are events from the city's past that are coming back to haunt Matilda in the form of a ghost.
One possible theme could be loss of innocence. If the princess has 'fallen', she may have lost her pure and naive self. Another theme could be about connection with nature if the black panda plays an important role in the story.
As I don't know the story, I can't say for sure who Tanja Darke is in it. She could be the main character, perhaps a hero or a protagonist facing various challenges.
One possible theme could be redemption. As Thor is in a 'fallen' state, the story could revolve around him trying to redeem himself in the eyes of his people or in his own eyes.
One possible theme could be heroism. There were many heroes on 9/11, from the firefighters who rushed into the burning buildings to the passengers on Flight 93 who fought back against the hijackers.
One of the main themes is the power of knowledge. Matilda, despite her young age, has a thirst for knowledge which helps her overcome the difficulties in her life. Another theme is the fight against injustice. Matilda has to deal with the cruel adults in her life like Miss Trunchbull, and she uses her intelligence to stand up to them.
A theme that often shows up is Matilda standing up against new forms of oppression or unfairness. In the original story, she fought against her cruel parents and the mean headmistress. In fanfiction, she might encounter different villains or unjust situations in her community or a new school she attends, and she uses her intelligence and powers to fight for what's right.
Well, there's the theme of unexpected setbacks. Like bad weather during an outdoor DCI event that ruins all the planned outdoor scenes. And then there's the theme of inexperienced leadership. If the person in charge doesn't really know what they're doing, it can lead to a whole host of problems, from poor casting decisions to mismanagement of funds and resources. It can be really detrimental to the overall success of the DCI project.
One possible theme could be love. In many short stories, love in various forms such as romantic love, platonic love or love for family is a common theme. Another theme might be self - discovery. The characters in the story could be on a journey to find out more about themselves. Also, it could be about survival, especially if the story is set in a difficult or dangerous situation.