Well, in fanfiction, Luffy's bond with Ace and Sabo is unbreakable. They grew up together and share a lot of memories. When it comes to the Marines, they represent the 'order' that Luffy and his brothers are sort of defying as pirates. Some fanfictions might show a young Marine recruit who has a change of heart after seeing the strong bond between Luffy, Ace, and Sabo. He starts to question whether the Marines are always in the right. Usually, though, the Marines are there to create conflict for the trio.
One interesting storyline could be Ace and Luffy teaming up against a powerful marine squadron. They might use their unique abilities, like Ace's fire powers and Luffy's stretchy attacks, to outwit the marines. Another could be a story where Luffy tries to rescue Ace from a high - security marine prison, facing many challenges along the way.
In fanfiction, a recurring storyline is the Marines' attempts to undermine the brotherly bond of Luffy, Ace, and Sabo. They might try to spread false rumors or create misunderstandings between them. Another popular one is the story of a Marine defector who joins Luffy's crew after realizing the corruption within the Marine ranks. Also, there are stories that focus on the power - up of Luffy, Ace, and Sabo in relation to the Marines. For example, they might gain new abilities and then use them to outwit the Marines in a big battle. There could also be fanfictions that explore the emotional side of the Marines, like a Marine who feels guilty for having to fight against the brothers because he secretly admires their loyalty to each other.
Obviously, Ace and Luffy are the most popular. But other characters like Zoro from Luffy's crew are also often included. On the marine side, characters like Smoker are quite popular as he has a sort of grudging respect for Luffy. Also, Akainu is often included as the big bad marine that Ace and Luffy have to face off against.
Blackbeard's crew is also a diverse bunch. His more aggressive members like Burgess might be eager to start a fight with Luffy's crew. However, some of the more cunning members could be thinking of ways to use the situation to their advantage. They might try to manipulate Luffy or his crew into making mistakes. And if Blackbeard decides on a certain course of action, his crew would generally follow, but there could be some internal dissent depending on the situation.
Zoro would be deeply affected. He has sworn to follow Luffy and his death would be a huge blow. He might feel like he failed in his duty to protect the captain. He would likely become more withdrawn at first, but then focus on getting stronger to avenge Luffy if there was someone to blame for his death.
Well, in this fanfiction, Luffy could interact with the Marines in a more diplomatic way. Since he has the advantage of time travel, he might understand the reasons behind the Marines' actions better. So, he could try to negotiate or make deals with some of the more reasonable Marines. He could offer to help them with other threats in the One Piece world in exchange for them leaving his friends alone at Marineford.
You can try some popular fanfic websites like FanFiction.net or Archive of Our Own (AO3). These platforms usually have a wide range of fanfics, and you can search for 'ace escapes marines' in their search bars to see if there are any relevant stories.
Well, 'Luffy and Ace: Unbreakable Ties' is a fanfiction that I really like. It focuses on their childhood memories and how those shaped their relationship as they grew up. There's also 'Ace and Luffy's Great Escape' which is full of action. It shows their cleverness in getting out of difficult situations. 'Luffy and Ace: The True Friendship' is a must - read too. It simply and effectively shows the depth of their friendship.