One interpretation could be that it's a form of extreme fanfiction that combines two well - known series in a shock - factor way. Maybe the author was trying to create a new and disturbing narrative that stands out.
I'm not aware of a specific fanfiction with this exact plot. It could be a very dark and disturbing concept. It might be exploring some extreme 'what - if' scenario where Naruto, from the Naruto universe, is somehow thrust into the Five Nights at Freddy's (FNAF) world and meets a gruesome end. But this seems like a very niche and potentially inappropriate crossover idea.
Often, there's the victim who gets stuffed in the suit. This character could be an employee who made the wrong move in the haunted pizzeria. And then there are the animatronics like Freddy, Bonnie, and Chica which are usually central to the story as they are either the cause of the stuffing or part of the horror that the stuffed character experiences.
One interesting concept could be the psychological horror of being stuffed into a suit. It gives a sense of claustrophobia and the horror of being trapped in an inanimate object. Another could be the mystery behind who is doing the stuffing and why. It adds an element of suspense to the fanfiction.
It could be from a foreign land. Maybe some traveling merchants brought it to the Hidden Leaf Village. They lost it on their journey and Naruto just happened to stumble upon it.
Naruto could develop a more refined and sophisticated side. The suit symbolizes a new level of maturity. He might become more aware of the political and diplomatic aspects of being a ninja leader. For example, he starts to use more words and less brute force in negotiations.
The talking stuffed animal could also be a plot device. Maybe it holds a key to a mystery. For example, it could have a map hidden inside it that leads to a powerful weapon or a secret location that is crucial for the safety of the Hidden Leaf Village.
A common theme is the clash of two different universes. Naruto's ninja world with its magic and combat skills meets the horror - filled FNAF world. Another theme is the development of relationships within the harem. It could be about Naruto gradually getting closer to the various characters from both worlds.
There might be a fanfiction where the FNAF animatronics are brought into the Naruto world. The animatronics' strange and somewhat creepy nature would contrast greatly with the ninja world. The shinobi would be both intrigued and cautious of these strange mechanical creatures, and perhaps they would try to find a way to either use them or get rid of them.
The unique feature is the crossover aspect. Combining Naruto's ninja - filled world with the horror - filled FNAF world creates a very different and exciting setting. For example, Naruto's jutsu in the spooky FNAF locations make for some cool scenes.