A possible plot could be that in the world of Earthbound, a new threat has emerged that is related to the pasts of Ness, Lucas, Ninten and Claus. The threat is causing disruptions in the fabric of their worlds. They are all brought to a central location, the Claus Camp. Here, they start to train together, learning about each other's powers and abilities. As they train, they uncover secrets about their families and the origins of their powers. They then set out on a quest to find the source of the threat. Along the way, they have to deal with internal conflicts, like Ness and Lucas having different approaches to problem - solving, and Ninten and Claus having trust issues. But through their adventures, they become a tight - knit group and are able to face the final showdown with the threat.
One idea could be a story where Ness, Lucas, Ninten and Claus are all brought together by a strange psychic phenomenon. They have to team up to figure out what's causing it and how to stop it. Along the way, they share their different experiences from their respective adventures and learn from each other.
One common theme could be friendship. Given the nature of these characters, fanfics might explore how Ness, Lucas, Ninten, and Claus form deep bonds with each other. Another theme could be adventure, as they all come from a world full of strange creatures and phenomena in Earthbound. They might embark on new adventures together.
I'm not sure of specific fanfics for this combination off - hand. But you can try looking on fanfic websites like Archive of Our Own (AO3). They usually have a large collection of fan - created works, and you can search using the relevant tags like 'Earthbound', 'Ness', 'Lucas', 'Ninten', and 'Claus' to find what you're looking for.
Perhaps a fanfic where Ness is on a journey to a new land and stumbles upon Lucas who is in trouble. Ness helps Lucas out and from there, they embark on a journey together. Along the way, they learn about each other's cultures and the unique aspects of their homes.
Another plot point could be a misunderstanding between Ness and Lucas at first. Maybe they misjudge each other's intentions due to the differences in their upbringing and the worlds they come from. But as the story progresses, they clear up the misunderstanding and become friends. For example, Ness might think Lucas is too soft because he comes from a more rural world, while Lucas might think Ness is too brash from his urban - like world in Earthbound. As they face challenges together, they see each other's true selves.
A common theme could be friendship. Since Ness and Lucas are both from the same game universe, their relationship can be explored in terms of a deepening friendship.
The fanfic might focus on Claus and Ninten's journey in the Smash world. They could be on a quest to prove themselves. They might face challenges like adapting to the different stages and rules. For example, they could struggle with the platform - based stages at first but then master them with practice. They may also form alliances with other characters during tournaments within the fanfic's story.
The plot is key. It could be an adventure story where they team up to face a new threat in their world. Or it could be a more emotional, character - driven plot about their friendship evolving into something more. Good fanfictions also have engaging writing styles that draw the reader in and make them care about what happens to the characters. This might include vivid descriptions of the settings and the characters' feelings.
One common theme could be friendship. Since they are characters from the same universe, their relationship might be explored in terms of how they become friends and support each other. Another theme might be adventure, as they could go on quests together in the fanfics.
There's a fanfiction titled 'Ness and Claus: Bond of Friendship'. This one focuses more on the building of their friendship. It shows how they start from being just acquaintances to becoming really close friends who support each other through different challenges in their world. It has some really heartwarming scenes.