In the Chronicles of Narnia, Peter and Susan Pevensie are a great brother - and - sister pair. As they enter the magical world of Narnia, they take on leadership roles. Peter is brave and becomes a great king, while Susan is gentle yet strong. They protect their younger siblings and help lead Narnia through various adventures and battles against the White Witch and other threats.
A good brother - and - sister pair in fiction often has complementary personalities. Take Sam and Ellie from the movie Up. Sam is a young Wilderness Explorer who is full of energy and curiosity. Ellie, his sister, is more laid - back and nurturing. Their different personalities work together well. They support each other in their adventures, whether it's Sam trying to earn his Wilderness Explorer badges or Ellie helping him out when he gets into trouble. They are a great example of how different personalities can create a strong bond in a fictional sibling relationship.
Kiba could also be a good match. If Naruto's sister has an affinity for animals like he does, they could bond over their love for their respective animal companions. They could train together, and their combined skills with their animal partners could make them a formidable duo in battles and missions.
Bruce Banner might be a good match as well. Since he's a scientist like Tony, his relationship with Tony's sister could involve a lot of scientific discussions. And with his struggle with the Hulk, she could be the one to help him find more balance in his life, which would be a really heartwarming and engaging plot in the fanfiction.
Ezra could be an interesting character to pair with her. He's a teacher, so there could be a mentor - mentee type of relationship that develops into something more. His mysterious past could also add an element of intrigue to the story.
I think a character like Leo would be great to pair with Ainsley. Leo is kind - hearted and adventurous, which can create interesting dynamics with Ainsley. Another good one could be Mia. She's smart and has a strong personality, and she and Ainsley could have some really engaging conversations and adventures together.
Bill Cipher is an obvious choice. Since they are both from the same 'universe' in Gravity Falls and seem to have some sort of connection already. Their interactions can create really interesting and often chaotic storylines.
Uraraka could also be a great pairing. They could be really good friends, with Uraraka's positive and friendly nature bringing out the best in Izuku's little sister. They might study together, train together, and support each other through the challenges of being at the hero school. Uraraka could also introduce her to new friends and experiences.
One of the best big brothers in fiction is Fred Weasley from the 'Harry Potter' series. He is kind - hearted and looks out for his younger siblings, especially George. They are always together, sharing adventures and having each other's backs in the wizarding world.
One great story is about a brother and sister who started a small gardening project together. They planted various flowers and vegetables in their backyard. They worked side by side, from preparing the soil to watering the plants daily. Through this, they learned about responsibility and shared many laughs when the first little green shoots emerged.
The title of this online novel from a long time ago might be The Contract Between Siblings.