A plot could revolve around Orihime getting lost in Hueco Mundo and Grimmjow being the one to find her. Instead of harming her as he might have in the original story, he decides to help her find her way back. Along the way, they start to see each other in a new light and form a bond based on mutual respect and friendship. Or perhaps they both end up in a strange dimension where they have to rely on each other's skills to survive and escape, and this experience changes their relationship for the better.
Yes, there are many. You can start by looking on popular fanfic platforms like FanFiction.net or Archive of Our Own. Search for 'grimmjow x orihime' and then filter out the mature or 'lemon' tagged ones. There are often great stories that focus on their relationship development, character interactions, and adventures within the Bleach universe without the explicit content.
Another theme is redemption. Sometimes Grimmjow is portrayed as seeking redemption through his relationship with Orihime. His past actions are often explored, and Orihime's influence is seen as a way for him to change for the better.
A plot idea could be that Naruto and Karin are paired up for a special training mission. During this mission, they have to learn a new jutsu together. As they practice, they face difficulties and have to rely on each other's strengths. Karin's knowledge of chakra and Naruto's determination combine to help them succeed in mastering the jutsu, and in the process, they become good friends.
One idea could be a story where Samus gets lost in Zelda's world and Zelda helps her find her way back home. Along the way, they discover new places and secrets in Zelda's world. Another could be that they are both summoned to a mysterious realm and have to work together to escape. They use their different abilities, like Samus' combat skills and Zelda's magic, to overcome obstacles.
One idea could be that Ichigo, Rukia, and Orihime discover a strange lemon - shaped spiritual artifact. They have to figure out its powers and how it relates to the Soul Society. Maybe it has the power to enhance their spiritual abilities, but also comes with a strange side - effect that changes their relationships in unexpected ways.
A third plot idea is that the reader is a new inhabitant in the Underground and they accidentally stumble upon Mettaton's secret rehearsal space. Mettaton is initially angry but then realizes the reader has some unique ideas for his show. So they start working together to improve his act. This could involve the reader teaching Mettaton some new moves or concepts from the human world that he hadn't thought of before.
One idea could be that Ash discovers a rare and powerful Pokemon that has been injured. He takes it upon himself to nurse it back to health. During this time, they form a deep bond based on trust and mutual respect. The Pokemon then decides to join Ash on his journey, and they face many challenges together, learning new moves and strategies along the way.
A third plot idea is a body - swap situation. Due to some magical mishap, Naraku and Kagome swap bodies. They are forced to live in each other's shoes for a while. Naraku, in Kagome's body, has to deal with her family and friends, and Kagome, in Naraku's body, has to face his minions and the other demons. This situation makes them understand each other better. As they try to find a way to reverse the spell, they start to see each other in a new light and develop feelings that were not there before.
A great plot could be that they are both invited to a superhero convention (in - universe). There, they get into all sorts of comical situations, like Deadpool trying to sell autographed pictures of himself and Spider - Man having to deal with over - enthusiastic fans. Along the way, they also discover a plot by a villain to disrupt the convention.
A really interesting plot could be that the reader has the ability to see the future in dreams, but the dreams are very cryptic. Percy and the reader have to work together to decipher these dreams to prevent a great disaster from befalling Camp Half - Blood. This would involve a lot of mystery - solving, and their relationship would develop as they rely on each other more and more to save the day.