Well, perhaps in this fanfic, Chell returns to find that Aperture has been taken over by a new, unknown force. This could lead to her having to team up with former enemies to fight against this new threat. Also, her journey through the now - dilapidated and overgrown parts of Aperture might be filled with puzzles that are both new and reminiscent of the old ones.
Chell is obviously going to be one of the main characters since she's in the title. GLaDOS is also very likely to be a main character as she was a central figure in the Aperture Science world. There could also be other test subjects if the fanfic decides to expand on that aspect.
Well, one interesting plot point could be how Naruto copes with being banished in the first place. Maybe he discovers new powers or allies during his time away. Another could be his grand return and how the village reacts to him, whether they welcome him back with open arms or are still skeptical.
In this fanfic, perhaps Minato's return causes a stir in the Hidden Leaf Village. His presence might change the political dynamics as the villagers remember his great leadership. He could also be involved in training the new generation of ninjas, especially Naruto's friends, to face new threats.
One interesting plot point could be Greninja's reunion with its trainer. Maybe after a long separation, there are new challenges they face together in the Alola region. Another could be Greninja's unique abilities being put to the test against new and powerful Pokemon in Sun and Moon.
One interesting plot could be Chell and Wheatley going on an adventure through uncharted areas of the Aperture Science facility. They might encounter strange and new test chambers that challenge their friendship and survival skills.
One interesting plot point could be Naruto's reunion with his old friends. He might share his new experiences and skills, like new jutsu he learned during his time away. Another could be how the village has changed in his absence, with new buildings or new generations of ninjas emerging.
Another possible plot point is that Naruto's return changes the political situation in Konoha. He could have different ideas about how the village should be run after seeing other places. He might challenge the existing council or propose new policies for the ninja academy to improve the training of young ninjas. His influence could also extend to the relationships between different ninja clans in Konoha, either strengthening or straining them depending on the nature of his changes.
Well, the fanfic could start with Chell being exposed to an experimental AI technology. This AI could start to influence her thoughts and actions in unexpected ways. Maybe it gives her enhanced cognitive abilities which she uses to explore a mysterious world. Along the way, she has to deal with the ethical implications of being so closely tied to an AI.
Well, in this fanfic, it could be that Chell discovers an ancient AI. The AI has unique powers and knowledge. Chell starts to learn from it and as she becomes more involved with the AI, she begins to change. She might gain new abilities or a different perspective on her world. For example, the AI could show her hidden secrets about the place she lives in, and together they could explore new areas or fight against some sort of oppression in her world.
Perhaps the fanfic focuses on Chell's character development as she becomes a core. It might involve her facing various challenges and obstacles that test her newfound identity. She could start off as an outsider but gradually gain the respect and recognition of the other elements related to the core through her determination and unique skills.