One of the great fanfictions might be those that explore their unique relationship within the horror - filled world of FNAF SL. It could be about how they interact during the 'nightshifts' in the game. Maybe there's a fanfic where they team up against some common threat in the animatronic world.
Foxy in these fanfictions is frequently portrayed with a sense of loyalty. He might be the type to stay by the Reader's side through various dangerous situations in the FNAF world. His broken - down appearance in some versions of the game also adds to the pathos in the fanfictions. Writers often play on his 'outcast' status among the other animatronics, which can make for some interesting relationship dynamics with the Reader.
One possible scenario could be that in the fanfic, Foxy runs away because he's scared of something in the pizzeria. Maybe he's afraid of the new security measures that are being put in place which he doesn't understand. As for the Foxy x Reader part, perhaps the reader is the only one who can understand Foxy's distress and tries to find him.
You can start by looking on fanfiction websites like Archive of Our Own (AO3). It has a large collection of FNAF - related fanfictions, and you're likely to find some good ones about Funtime Freddy and Funtime Foxy there. Just use the search function and type in their names.
Obviously, Foxy and the reader are the main characters. Foxy is the animatronic character with its own personality and backstory within the FNAF universe. And the reader is the character through whose perspective the story is often told.
In a 'FNAF Foxy Runaway Foxy x Reader Fanfic', the plot might involve the reader being in the wrong place at the right time. Foxy is on the run from the other animatronics or some other threat in the pizzeria. The reader and Foxy start to trust each other as they face various obstacles together. For example, they might have to avoid security guards or other animatronics that are out to get Foxy. As they spend more time together, a special relationship develops between them, which could be a friendship or something more romantic depending on how the author wants to write it.
A simple fanfiction could be that Foxy and Mangle meet for the first time. Foxy is curious about the strange new animatronic that is Mangle. They exchange glances and start to communicate in their own animatronic ways, perhaps through beeps and flashes. This could be the start of an interesting bond.
One great 'FNAF Foxy x Mangle Fanfic' is 'The Pirate and the Mangled One'. It really delves into their relationship in the spooky FNAF world. The way it describes their interactions makes it seem like they have a deep connection.
A prevalent theme is also the idea of acceptance. They learn to accept each other's quirks and flaws. For example, in some fanfictions, Freddy might be initially annoyed by Foxy's wild nature, but then grows to love it. Also, loyalty is a big part. They stay by each other's side through thick and thin.
I like 'Freddy and Foxy's Unlikely Bond'. In this fanfiction, it explores how Freddy and Foxy, who seem so different at first, gradually form a deep friendship. It's full of heartwarming moments and some exciting action scenes too.