District 9 is a (technically) South African science fiction film directed by Neill Blomkamp and released in 2009. Produced by Peter Jackson, it is both an expansion on Blomkamp's previous short film Alive in Joburg and the result of what happened once the proposed Halo movie had completely fallen apart.
District 9 concerns an alternate universe in which an alien ship comes to hover above Johannesburg, South Africa. Rather than take over the world, however, it turns out that these aliens are refugees, apparently running away from something. After about 20 years, though, their lot isn't much better: the aliens all live in the titular township just outside of Johannesburg, and they are managed by Multi-National United (MNU), an international arms manufacturer who take quite a bit of interest in the weapons the aliens bring with them. To make matters worse, there are plans to relocate the aliens at the time the movie begins. However, while relocating aliens within the district, MNU worker Wikus van de Merwe comes into contact with an alien substance and winds up undergoing a very bizarre transformation. Things may just change in Johannesburg forever.
The movie had a large viral campaign, spanning across several websites and a few odd street signs saying something to the effect of "non-humans are not welcome." The movie is an apartheid allegory, and was made under an impressively tight budget.
District 9 in Fanfiction
Thankfully, the universe of District 9 is given a lot of development in-movie. Even the mundane details are touched upon, which makes for a fandom that usually tries to get all the details right.
A common trait in fanfiction is to refer to the aliens as "poleepkwa." Nobody ever refers to them as this in the movie itself, but fans have used it as an alternative because it was used at one point in Alive in Joburg. There is also the fact that the only term we're given in movie ("prawn," after the Parktown prawn) is considered very offensive in-universe.
This trait characterizes the small but dedicated fanon that has sprung up around the movie. Many fanfics tend to share the same original characters, and in this they get rather interconnected.
The kinds of fanfiction for District 9 vary. However, perhaps most common is, surprisingly enough, slash with Wikus van de Merwe and Christopher Johnson, the main alien character of the movie. This is despite the fact that a) it's firmly established in canon that Wikus has a wife he loves to death, and b) the aliens in the District 9 universe are hermaphroditic (though the second point is justifiable in that the character has a male name). Other fanfiction involves imaginings of District 10, things surrounding the events of the movie, and sometimes even events before the start of the movie.