The animatronics can be developed by giving them individual personalities. For example, Freddy could be the more authoritative one among them, while Chica could be a bit more unpredictable. You can also show their backstories through flashbacks or by having Tyler discover old records in the pizzeria. This way, they become more than just scary monsters but complex characters with their own motives.
For Tyler, you can start by giving him a clear backstory. Maybe he's a big FNAF fan, so he has a lot of knowledge about the lore which he can use to his advantage. His reactions to the dangerous situations in the pizzeria should be realistic, like being scared at first but then gradually getting more determined.
A more complex plot could be that Tyler is actually a reincarnation of someone who was wronged in the FNAF backstory. The animatronics sense this and are initially hostile, but as Tyler starts to remember his past life, he is able to use his knowledge to try and bring peace to the pizzeria. He might have to face off against an evil force that has been using the animatronics for its own malevolent purposes.
To develop Mike, you could make him start off as a very skeptical person about the animatronics. But as he spends more time with them, he starts to see them in a different light. You can show his internal struggle between his rational thinking and the strange things he experiences with the animatronics. Regarding the animatronics, each one can have a backstory. Chica might have been programmed with a motherly instinct, and as she gets to know Mike, she tries to 'care' for him in her own animatronic way. This helps to flesh out their characters.
Tyler, as a male OC in FNAF fanfiction, can bring a fresh perspective. He could be a new night guard, facing the terrors of Freddy Fazbear's Pizza. His character might have unique traits like extraordinary courage or a special backstory that makes his interactions with the animatronics interesting.
In FNAF fanfiction, a male Tyler OC might be designed as a tech - savvy character. He could be trying to figure out the secrets behind the animatronics' glitches and abnormal behavior. This OC could add new plotlines to the already complex world of FNAF, like attempting to reprogram the animatronics to stop their murderous tendencies.
For Jeremy, his character could be developed further by exploring his relationship with his new - found powers in more depth. He could struggle with the moral implications of using them, and Tyler could be there to offer a different perspective. Tyler, on the other hand, could be developed by showing more of his softer side. Maybe he has a passion for art or music that no one knows about, and Jeremy discovers it.
The male Tyler OC can act as a catalyst in the FNAF fanfiction story. He might be the one to start uncovering the dark secrets of the pizzeria. For instance, he could find hidden rooms or documents that reveal the true nature of the animatronics.
For male characters, showing their vulnerability is important. For example, a male character might be really strong on the outside but have fears deep inside. For female characters, highlighting their intelligence and independence is great. Like a female detective who solves a complex case on her own.
To write Foxy well, remember his speed and stealth. Describe how he moves quickly through the pizzeria, his red eyes glowing in the dark. When it comes to Mangle, show its confusion. Since it's often in pieces, it might not be as sure of itself as Foxy. You can write about how it tries to figure out its own form and purpose, and how Foxy can either help or hinder this process.
Tyler can be the protagonist, leading the story through the spooky world of FNAF. His journey could be about survival, uncovering secrets, or both.
For the OC, you can start by giving them a unique backstory. For example, if they had a difficult past that made them more empathetic towards Koneko's own struggles. Koneko's personality is already somewhat reserved and strong - willed. The OC can gradually draw her out of her shell by being patient and kind. Maybe the OC has a sense of humor that Koneko slowly starts to appreciate, and this helps in developing her personality to be more open and less stoic.