Perhaps they could be in a situation where they are both competing for a big opportunity, like a scholarship or a lead role in a musical, when they find out about the pregnancy. This would add a layer of conflict as they have to decide between their dreams and the new life they are about to bring into the world.
Another idea is that Santana discovers she's pregnant after Finn has already left town for some reason. She then has to track him down to tell him the news, and along the way, she has to face her own insecurities and fears about being a single mother. Meanwhile, Finn is dealing with his own issues in the new place and has to come to terms with the sudden change in his life.
A more complex plot could be that they are not sure who the father really is. This creates a lot of drama and tension. They could go through a process of trying to find out the truth, all while dealing with the fact that they are about to become parents. Their relationship might be on the rocks because of the uncertainty, but in the end, they realize that no matter what, they want to raise the baby together.
Another plot could involve Santana's career aspirations while being pregnant. If she has a high - flying career, she may struggle to balance work and pregnancy. She could face discrimination at work or have to fight to keep her job, which would add a lot of drama to the fanfiction.
One plot idea could be that they are unexpectedly pregnant and have to deal with the reactions of their families and friends. Maybe they initially struggle with the idea but then come to terms with it and support each other through the pregnancy.
Another possibility is that there's some confusion at first. Maybe a false positive pregnancy test leads to a rollercoaster of emotions for them. They could start planning for a baby only to find out later it was a mistake, but this experience could bring them closer as a couple.
One possible plotline could be Santana's journey of self - acceptance after being outed. Finn's actions might lead to a rift in their friendship at first. Then Santana could start to find her own voice within the Glee club, standing up not only for herself but also for other members who might be facing similar issues. For example, she could use her new - found visibility to advocate for more inclusive song choices in the club.
One idea could be Finn getting a bad case of the flu right before a big performance. His friends in Glee club would then have to figure out how to cover for him or help him get better in time. Another could be that Finn has an ongoing illness that he's been hiding from the club, and it finally starts to affect his ability to participate fully. Maybe he faints during a rehearsal, and then everyone rallies around him to support him through his sickness.
A really cool idea for a fanfiction could be that Rachel and Finn swap personalities for a day. Finn suddenly becomes super - focused on his Broadway dreams like Rachel, and Rachel has to deal with Finn's more laid - back attitude towards things. It would be a humorous and also a great way to explore their relationship from a different perspective.
Perhaps a plot where Finn accidentally gets turned into a vampire - like creature due to one of Marceline's experiments gone wrong. They then have to figure out how to reverse it while also dealing with the new powers and instincts Finn has. Along the way, they learn more about each other's insecurities and fears, strengthening their bond as friends.
The plot could involve Santana hiding her pregnancy at first from most of the Glee club members. She's afraid of the judgment and how it might change things. But as her pregnancy progresses, it becomes harder to hide. Her friends start to notice the changes in her behavior and body. Eventually, she has to come clean, and they all rally around her to support her through the pregnancy.
One idea could be that Captain Phasma and Finn are forced to team up during a mission gone wrong. They start off distrusting each other but as they face various challenges, they gradually come to respect one another's skills. For example, they might have to fight against a new and powerful enemy force that neither of them can handle alone.