One possible plot could be that the Teenage Mutant Ninja Turtles somehow end up in the Freddy Fazbear's Pizza place. Maybe they are investigating some strange disappearances that are rumored to be related to the animatronics. They could use their ninja skills to navigate the dark hallways and face off against the haunted animatronics. The turtles' unique personalities would add a fun dynamic, like Mikey being scared at first but then finding the whole situation exciting, while Raph is ready to fight from the start.
In a tmnt and fnaf crossover fanfiction, it could be that the FNAF animatronics are brought to New York by some evil force. The Turtles then have to protect the city from these menacing creatures. The animatronics' spooky nature and the Turtles' combat abilities would create an interesting contrast. Splinter could also play a role, perhaps giving the Turtles some ancient wisdom on how to deal with these otherworldly threats. And April and Casey could get involved too, helping the Turtles in different ways.
Well, maybe the Dementors in Harry Potter are somehow related to the animatronics in FNAF. The Dementors' ability to suck out souls could be connected to the animatronics' seemingly menacing behavior. A fanfiction could explore how the wizarding world's magic could either control or be affected by the FNAF animatronics. For example, could a Patronus charm work against them? And what if a character like Fred and George Weasley decided to prank with the animatronics, not realizing the real danger.
Well, it could be that one of the FNAF animatronics gets sent to the Loud House world by accident. Let's say Freddy. Freddy then starts to interact with the family. He might mistake the Loud family for the pizzeria staff. Lincoln and his sisters would have to work together to either fix Freddy and send him back or find a way to co - exist with him. The younger siblings like Lily might be curious about Freddy rather than scared at first, which could add a cute element to the otherwise potentially spooky crossover.
One possible plot could be that the Turtles end up in the Valley of Peace. They meet Po and his friends. Po is initially shocked by these strange new creatures but quickly realizes they all share a love for kung fu. Together, they have to face a new villain who has the power to disrupt both their worlds. The Turtles' unique fighting styles combined with Po's clumsy yet effective kung fu could make for some great action scenes.
One idea could be that the Turtles from 2003 get transported to the 2012 universe and they have to deal with the different versions of their enemies. For example, the Shredder in the 2012 version might have some new powers or tactics that the 2003 Turtles aren't used to.
A possible plot is that an ancient evil that was sealed away in the 2003 universe is accidentally awakened by the arrival of the 2012 turtles. The 2003 turtles initially blame the 2012 ones but then realize they need to work together. They combine their strengths, with the 2012 turtles' modern thinking and the 2003 turtles' deep knowledge of ancient ninja lore, to defeat the evil.
One idea could be that the Turtles from 1987 end up in the 2003 universe and have to adapt to the darker and more serious tone. They could team up with the 2003 Turtles to fight a common enemy like the Shredder. The 1987 Turtles' more light - hearted and comical ways might initially clash with the 2003 Turtles' brooding nature, but they eventually learn from each other.
One idea could be that the Turtles end up in the Underground world of Undertale. They might have to navigate through the various regions, like Snowdin or Hotland, using their ninja skills. For example, they could use their stealth to avoid some of the more dangerous monsters. Another plot could involve the characters from Undertale being brought to the Turtles' New York. They would then have to deal with the Foot Clan and other threats in this new, strange environment.
One idea could be that Foxy from FNAF crosses over into another universe where he teams up with a group of unlikely heroes. Maybe he uses his speed and stealth to help them in a battle against a common enemy.
One plot idea could be that the characters from MyStreet end up in the FNAF pizzeria. They initially think it's just a strange place but soon realize the danger of the animatronics. Another idea is that the FNAF animatronics somehow enter the MyStreet world and start causing chaos among the peaceful MyStreet community. For example, Freddy might try to take over the local diner in MyStreet, thinking it's his territory.
A possible plot could involve the souls in Undertale having some connection to the spirits that are rumored to be in the FNAF animatronics. The main character from Undertale, perhaps Frisk, could enter the FNAF world and try to free the trapped souls. In return, the animatronics could help Frisk in the Undertale world against some powerful foes.