There are fanfictions that might focus on a side character from 12x16 and give them more backstory. For example, a story about a hunter they met briefly in the episode who has their own secrets and motives. These stories can add new layers to the already rich Supernatural universe.
One great Supernatural 14x13 fanfiction could be about exploring the unshown emotional aftermath of the events in that episode for the characters. For example, a story might focus on Dean's internal struggle that wasn't fully shown on screen. Another could be a story that takes a side character from that episode and gives them more backstory and a new adventure in the Supernatural universe.
One interesting story could be about the characters facing an unexpected new villain. Maybe it involves a powerful demon that has a unique connection to Sam or Dean's past. It could add a whole new layer of mystery and danger to their adventures.
One great 'Supernatural' fanfiction could be those that focus on the Winchester brothers' relationship deeper. For example, stories that explore their childhood traumas and how it shapes their bond in a more detailed way. There are also fanfics that introduce new and interesting characters in the 'Supernatural' universe.
There's a fanfiction titled 'Hidden Truths in 14x12'. It focuses on the secrets that might have been lurking beneath the surface during the episode. It's really interesting as it explores different theories that fans might have had about that particular episode.
Sorry, I don't have a specific list of 'supernatural 12x09 fanfiction' to recommend. But you can try looking on fanfiction websites like Archive of Our Own or FanFiction.net. There you can search for fanfictions related to that specific episode and read reviews to find good ones.
You can try looking on Archive of Our Own (AO3). There are often a lot of great fanfictions related to Supernatural episodes. Just search for 'Supernatural 14x17' and you'll find a variety of works with different themes and writing styles.
I really like 'Supernatural at Hogwarts'. In this fanfic, the boys from Supernatural are transported to Hogwarts. It's fun to see how they adapt to the magical school environment. Sam is the more studious one, trying to learn all about magic, while Dean is more interested in finding out if there are any real monsters lurking in the Forbidden Forest. And of course, there are lots of crossovers with the original Harry Potter characters which makes it exciting.
Well, there's a fanfic called 'Stiles: The Chosen One'. In this story, Stiles is revealed to be some sort of chosen one with special powers that are crucial for saving the supernatural world from a great evil. Then there's 'Stiles in the Supernatural Realm'. This one takes Stiles on a journey through different parts of the supernatural realm he didn't even know existed, and he has to adapt quickly to survive. Also, 'Mystical Stiles' is a fanfic that dives into Stiles' connection with ancient supernatural forces and how he uses them to protect his friends.
One great narusasu supernatural fanfiction could be 'The Spirit Bond'. It's about Naruto and Sasuke having a special connection in a world filled with spirits. They have to team up to fight against an evil spirit that is threatening their village.
One great Buffy Supernatural fanfiction is 'The Crossover Quest'. It combines the two universes in an exciting adventure where Buffy and the Supernatural gang team up to fight a new, powerful evil. The characters are well - written and it stays true to the essence of both shows.