No. It is not acceptable. Fan communities usually strive to be inclusive and family - friendly places. Sexual fanfic like this violates the norms of respect and decency that most communities uphold.
'Vanny sex fanfic' involves creating fictional and often inappropriate sexual stories related to the character Vanny. Such content is inappropriate because it goes against ethical and moral standards. Fanfiction should generally focus on positive, creative and non - offensive aspects of a character or a fictional world.
One interesting plot could be Glitchtrap slowly influencing Vanny's actions in the virtual world and how she then starts to carry out his sinister plans in the real world. For example, he might manipulate her into setting up traps for the other characters in the game's setting.
Many fanfictions depict it as a somewhat symbiotic relationship. Vanny gets power and a sense of purpose from Glitchtrap, while Glitchtrap uses Vanny to achieve his goals in the game world. They depend on each other in a twisted way.
Definitely not a true story. FNAF is a work of fiction that takes place in a fictional world with its own set of rules and scenarios. It's all about creating a thrilling and immersive gaming and storytelling experience, not reflecting reality.