A new Titan could emerge as the main antagonist. Maybe one that was hidden away all this time and now has awakened to seek revenge on the demigods. This Titan could have unique powers that the demigods have never faced before.
One idea could be Percy waking up in a new world where the Greek gods are unknown, and he has to start from scratch to regain his powers and find his friends. He could face new monsters that are a mix of modern and mythological threats.
Imagine a fanfic where Percy has to navigate the New York City traffic while being chased by a pack of hellhounds. He has to use his water - based powers in creative ways, like creating water slides on the streets or using sewer water to slow down the hellhounds. This would be a really action - packed and fun story.
One great fanfic idea could be Percy Jackson exploring the hidden magical corners of New York City that are unknown even to most demigods. Maybe he stumbles upon an ancient artifact in an abandoned subway tunnel that has the power to either save or destroy the city.
First, you need to know both universes well. For 'New Girl', understand the characters' personalities like Jess's quirkiness, Nick's laid - back nature, etc. For 'Percy Jackson', know about the demigods, the gods, and the world of Camp Half - Blood. Then, think of a unique plot. Maybe the New Girl characters discover they are demigods. Or the Percy Jackson characters visit the loft in 'New Girl'.
It could start with Percy being spotted by S.H.I.E.L.D. agents while using his powers. They report back to Nick Fury, who becomes intrigued. Fury then decides to approach Percy himself to find out more about this 'powered individual'.
First, you should familiarize yourself with both universes. Read the Percy Jackson books and play Undertale. This will give you a good understanding of the characters, settings, and storylines. Then, think of an interesting concept for the crossover, like how the two worlds could meet or interact.
First, think about the kind of homework Percy might get. Is it related to Greek mythology, like a research paper on a particular god? Then, consider his reaction to it. For example, if it's a boring math homework, he might be really frustrated. Start with a simple scene, like Percy sitting at his desk in Cabin 3, looking at the assignment. Then, introduce some conflict, like his ADHD making it hard for him to focus, or a sudden visit from Grover that interrupts him.
First, think about the characters you want to focus on. It could be the old favorites or new ones. Then, come up with a basic plot idea, like a new adventure or a mystery at Camp Half - Blood. Start with a strong opening, like a demigod in a dangerous situation.
Well, it could be about Percy starting a new life in a different realm, away from all the chaos he usually faces. Maybe he discovers new powers or makes entirely new friends there.