One interesting plot idea could be Castiel protecting Kelly from various supernatural threats as she is pregnant. Maybe they have to go on the run and hide in different places, leading to some heart - to - heart conversations between them about the future of the baby and their own fates.
Another plot could be that Kelly discovers a hidden power within herself and Castiel helps her to control it. They could form a bond not just of protector - protectee but also as equals in a way, with Castiel learning from Kelly's strength and determination.
Another idea is that Castiel's drunkenness causes him to lose his usual grace - filled composure and he starts to behave in a very un - angel - like manner. He could get into comical situations, like trying to dance at a local bar and attracting all kinds of strange looks. This could also lead to him making new, unexpected friends who help him in a future battle in an unorthodox way.
Perhaps they could discover some family secrets during the pregnancy. For example, there could be a long - lost relative who suddenly shows up with their own ideas about the baby. Also, they might struggle with financial issues as they realize how expensive having a baby can be and have to find creative ways to save money.
One possible plot twist could be that Castiel kidnapped the character not out of malice but to protect them from a greater threat that the other characters are unaware of. For example, there might be a powerful and hidden enemy that has targeted this particular character, and Castiel believes that by taking them away, he can keep them safe.
One plot idea could be that the reader is a hunter who has lost their faith, and Castiel helps them regain it. He shows them the good in the supernatural world and that not all angels or other beings are bad. Along the way, they form a deep bond based on mutual understanding and respect.
One idea could be Castiel getting transported to the Harry Potter world. Maybe he tries to understand the magic there using his angelic knowledge. Another plot could involve Castiel teaming up with Harry Potter to fight a common dark force that is threatening both the wizarding world and the Supernatural world.
One plot idea could be that the OC is a new firefighter at the station. Kelly Severide initially doubts the OC's abilities but as they work together on various tough calls, he comes to respect and even develop feelings for the OC. For example, during a large warehouse fire, the OC shows great courage and quick thinking which catches Kelly's attention.
A plot could involve Gustavo and Kelly in a time - travel situation. They get sent back to their early days in the music industry. They see how they started and how they've changed. As they try to find their way back to the present, they have to rely on each other more than ever. This could bring out different sides of their relationship, like a deeper friendship or the realization of hidden feelings.
One plot idea could be a mission where Master Chief and Kelly are separated from the rest of their team. They have to rely on each other's unique skills to survive in a hostile alien environment. Another could be a story set in their early days of training together, exploring how their relationship began to form. Or perhaps a plot where they are faced with a moral dilemma during a mission and their different perspectives on it cause some tension between them at first, but ultimately they find a way to resolve it together.
One possible plot could be Castiel trying to understand the unique magical system of Hogwarts. He might initially struggle as his angelic powers work differently. For example, he could be confused by the use of wands when he's used to his own celestial abilities. But as time goes on, he starts to blend his knowledge with the wizarding world's, creating new spells or teaching methods that combine angelic and magical concepts.
Their relationship could be developed uniquely by having Kelly teach Castiel about human emotions in a more in - depth way. Since she is going through such a unique and intense experience being pregnant with a special child, she can share her feelings and perspectives that make Castiel see humans in a new light, thus strengthening their bond.