One common theme is redemption. Since Peter has made mistakes, many fanfictions focus on him trying to make up for his actions and win Alicia back. Another theme is love vs. career. Their relationship is often put to the test because of their busy careers, like Alicia's legal work and Peter's political career.
One interesting fanfiction could be about Alicia and Peter rebuilding their relationship after a major crisis. It might explore how they overcome their differences and learn to trust each other again. Maybe they go on a trip together to a place that holds special memories for them, and during that time, they have deep conversations that rekindle their love.
There's this fanfiction called 'Peter's Redemption'. It focuses on Peter's journey to redeem himself in Alicia's eyes. He tries to make amends for all his wrongdoings. Also, 'The Unspoken Bond' is quite interesting as it shows the unspoken connection that still exists between Alicia and Peter even during their toughest times.
You can start by looking on fanfiction websites such as Archive of Our Own (AO3). It has a large collection of fanfictions from various fandoms, and you're likely to find some great Alicia and Peter Florrick ones there. Just use the search function and type in their names.
Perhaps a fanfiction where Alicia has to defend Peter in a legal case against a false accusation. This puts her in a difficult position as she has mixed feelings about him. But as she delves deeper into the case, she discovers things about Peter she didn't know before and it changes the dynamic of their relationship.
I'm not sure which are the most popular ones specifically. But you can check fanfiction websites like Archive of Our Own. There are likely many stories that explore different aspects of Peter and Alicia's relationship, from their early days to the more tumultuous times.
Since I'm not familiar with this 'Alicia Online Thomas story', it could be about their adventures in the virtual world of Alicia Online. Maybe they are friends or partners in the game, and they go on quests together, fight against monsters, or explore new areas. But this is just speculation without more details.
I really liked the fanfiction titled 'Alicia Spinnet: The Unseen Heroine'. This story gives Alicia a more central role. It weaves in her family history and how it impacts her actions during the events at Hogwarts. It also has some really interesting interactions between Alicia and other minor characters from the books, which gives a fresh perspective on the whole Harry Potter universe.
Perhaps she had a significant moment where she overcame a major food craving or temptation. This could be an important event as it shows her willpower. Another event might be when she reached a certain weight milestone in her journey, either losing a particular amount of weight or struggling to break through a plateau.