There is a fanfic titled 'The Bond of Chibiusa and Her Sister'. In this, it delves deep into how they support each other through different challenges in their magical world. It's a really engaging read as it also shows their growth as characters.
One popular theme could be the exploration of their relationship in different magical scenarios. For example, they might be on a quest together in a new, uncharted part of the magical world, which tests and deepens their bond. Another theme could be the power of their combined magic. Since they both have unique magical abilities, fanfiction often delves into how they use these powers to overcome challenges. Also, the theme of self - discovery within their relationship is quite common. As they interact more, they learn more about themselves and their place in the magical realm.
One popular 'chibiusa older sister fanfic' could be 'Chibiusa's Big Sister Adventures'. It often shows Chibiusa in different situations with her older sister figure, exploring their relationship and the challenges they face together.
Perhaps a story where Chibiusa has a dream on her seventh birthday. In the dream, she travels to a different time and meets her future self. Her future self gives her some advice and wisdom that she can use as she grows up.
Well, 'Journey of Hearts' is also a great one. It begins with a chance encounter between Gohan and Chibiusa. The story then delves into how they gradually open up to each other, sharing their hopes, fears, and dreams. It's a really heartwarming fanfic that shows their relationship developing in a very natural way.
Archive of Our Own (AO3) is another great place. It has a very organized tagging system. So, you can search for 'gohan x chibiusa' and it will show you all the relevant fanfics. There are also filters you can use to sort by things like word count or rating.
There's a fanfic called 'Friendship Beyond Magic: Chibiusa and Sister'. This one really emphasizes how their friendship is strong enough to overcome any magical obstacles. It shows how they rely on each other not just because they are sisters, but also because they are true friends.
To write your own Chibiusa and Helios fanfiction, start with an interesting concept. For example, what if Helios lost his powers and Chibiusa had to help him regain them? Outline your story with a beginning, middle, and end. In the beginning, introduce the situation or problem. In the middle, have them face challenges and obstacles while also building their relationship. At the end, resolve the problem in a satisfying way. Also, use dialogue effectively to show their personalities. Chibiusa might be more impulsive in her speech, while Helios could be more calm and wise.
Add some mystery. For example, hide a secret message in the story that Chibiusa has to figure out during her birthday. It could be a riddle left by a mysterious character.