One possible plot could be that they accidentally meet during a mission. Superboy is in a tough spot, and M'gann uses her powers to save him. This moment of vulnerability makes them realize how much they still care for each other. They start talking about the past, the good times and the mistakes. Slowly, they begin to trust each other again and rekindle their relationship.
In a fanfiction, it could start with M'gann having dreams about Superboy. These dreams make her question her feelings. She decides to reach out to him. Superboy, on the other hand, has been secretly missing her. When they meet, there's initial awkwardness. But as they start to communicate, they find that the love between them never really died. They start spending more time together, going on small adventures and eventually get back together.
The team would likely be very supportive. They know how much Superboy and M'gann meant to each other before. Their getting back together could boost the team's morale. It might also lead to better teamwork as Superboy and M'gann would be in a better mood and more focused. They could use their rekindled relationship as an example of second chances within the team.
One possible plot could be that after a long time apart, they accidentally meet at a place that holds significance for them, like the old Total Drama Island. Their initial encounter might be filled with awkwardness and old grudges resurfacing. But as they start talking, they realize they still have feelings for each other. Maybe Duncan has changed for the better during their time apart, and Courtney sees this new side of him that makes her fall in love all over again.
One possible plot could be that after a long time apart, Scott and Allison accidentally meet at a place that holds a lot of memories for them, like the high school where they first met. This encounter stirs up old feelings, and they start to talk about the past. Slowly, they realize that they still love each other deeply and begin to rekindle their relationship.
One possible plot could be that they meet by chance after a long time apart. Maybe at a Downworlder event where Magnus is using his magic to create some amazing display. Alec, who is there on some Shadowhunter business, can't take his eyes off Magnus. They exchange a few words, and the old feelings start to resurface.
One possible plot could be that they meet by chance at a music event. Maybe Jesse is performing and Rachel is in the audience. After the show, they start talking and realize they still have feelings for each other. They then slowly start rebuilding their relationship by going on dates and reminiscing about their old times together.
One possible plot could be that they realize they still have feelings for each other during a chance encounter. Maybe at a mutual friend's party. They start talking, reminiscing about the good times, and slowly the old spark reignites.
The plot could be that their children (in a sense, the characters they care about) play a role in bringing them back together. Maybe the characters notice how much Asgore and Toriel still have feelings for each other. They set up situations where Asgore and Toriel are forced to interact, like a dinner or a shared task. Through these interactions, old feelings resurface, and they get back together.
It could be that Cody is in a bit of a slump in his life and Bailey, who has always cared for him, comes to his aid. This act of kindness makes Cody realize how much he still loves her. They then start spending more time together, sharing their dreams and fears, and eventually, they get back together, much to the delight of their friends and family who always thought they were a great couple.
Well, it could be that Selina has changed her ways a bit and is now more involved in helping the underprivileged in Gotham. Bruce sees this new side of her and is drawn to her again. They start having secret meetings where they talk about their dreams for the city. These meetings slowly turn into romantic encounters as they realize they still have strong feelings for each other.
One possible plot could be that Naruto, in his godlike state, somehow ends up in the same universe as M'gann M'orzz. They initially clash due to their different upbringings and powers. Naruto's determination and M'gann's empathetic nature gradually bring them together. They start to understand each other's worlds and find common ground in their desire to protect those they care about. As they train together, their relationship deepens into a romantic one.