The Revolutionary Army would be likely to support the OC. They have been fighting against the World Government for a long time. If an OC attacks Mariejois, it aligns with their goals of overthrowing the current regime. They could provide resources, intelligence, or even military support to the OC in their attack.
Well, if an One Piece Original Character (OC) attacks Mariejois, it would be a huge deal. Mariejois is the center of the World Government's power. The Marines would surely mobilize to stop the OC. Maybe the Admirals would be sent to deal with this threat. It could also lead to a big shift in the power balance in the One Piece world as it challenges the very core of the established order.
There's no way to tell for certain who made the 'gavin oc one piece fanfic' without more information. It could be an amateur writer who just wanted to explore their own ideas in the One Piece universe. Maybe it was created by a small group of friends who were discussing what an original character like Gavin could do in the One Piece world and then decided to write it down as a fanfic.
The original character (OC) is also a main character. This could be a self - inserted character created by the fanfic writer, who has their own set of abilities, dreams, and flaws. They might be a pirate, a marine, or someone with a completely different role in the One Piece universe.
One of the best One Piece OC fanfics is 'The New Pirate's Adventure'. It has a really engaging story where the original character (OC) has a unique backstory and goals that fit well into the One Piece universe. The character development is great and the author manages to make the OC interact with the canon characters in a believable way.
In a One Piece fanfic, an OC (Original Character) as Luffy's rival could be really interesting. This OC might have a unique Devil Fruit ability that directly opposes Luffy's powers. For example, if Luffy has the Gum - Gum Fruit which gives him stretchy abilities, the rival could have a hardening or shrinking ability. This would create intense battles between them as they fight for different ideals on the Grand Line.
Maybe it's a new pirate crew led by a character with a Devil Fruit power that can nullify the OC's Gamer abilities. This pirate captain is extremely ambitious and wants to rule the New World. He views the OC as an obstacle in his path because the OC has the potential to disrupt his plans, especially if they can use their Gamer skills to form alliances against him.
Perhaps an existing 'One Piece' character could be turned into the main antagonist in the context of this fanfic. For instance, a marine officer who sees the OC as a threat to the world government's order. Since Viola has ties to Dressrosa, which has its own complex relationship with the world government, this marine could target them both. The officer might use underhanded tactics to try and stop the OC and Viola from achieving their goals.
An OC's Haki can be developed through intense training. Just like how Luffy and the others train in the One Piece world. They could face difficult opponents and learn from each battle, gradually strengthening their Haki. For example, if they constantly fight against Logia - type devil fruit users, their Armament Haki would improve to counter their intangible forms.
To create a compelling male OC in One Piece SI fanfiction, first, give him a clear backstory. Maybe he comes from a destroyed island or has a family mystery. Second, give him unique abilities or skills. It could be something like a special form of Haki or an unusual sword - fighting style. Third, give him a distinct personality, like being a bit of a trickster but with a good heart.
Well, 'one piece godlike oc fanfiction' might be stories where fans write about their own original characters in the One Piece world who are extremely powerful, like godlike. Maybe it's about an OC who can instantly travel between different islands without using a ship, or one who can heal any injury or disease in an instant. These fanfictions usually explore new and exciting scenarios that the original One Piece story might not have covered yet.