Maybe Rainbow Dash would play a prank on Fluttershy by hiding all of her little animal friends. She would do it in a harmless way, of course. She'd then pretend she has no idea where they are while Fluttershy starts to worry. Eventually, Rainbow Dash would bring them all back and have a good laugh with Fluttershy about it.
Most of the time, Rainbow Dash's pranks are in good fun. With ponies like Pinkie Pie, her pranks can strengthen their relationship. Pinkie Pie loves a good laugh and would probably find Rainbow Dash's pranks hilarious. They would bond over the shared humor and it would make their friendship even closer.
One popular Rainbow Dash fanfiction is 'Flight School Days'. It focuses on Rainbow Dash's early days at flight school, her struggles and how she overcame them. Another is 'Rainbow Dash and the Great Race' where she participates in an epic race across Equestria.
One interesting Rainbow Dash fanfiction could be about her training a new group of pegasi in the ways of speed and agility. It might show her strict but fair coaching style.
Some fanfictions might focus on Baby Rainbow Dash's relationship with her parents. They could be teaching her important values like honesty and loyalty. For example, a story could be about how her parents encourage her to always be true to herself and her friends, and through their guidance, she grows up to be the brave and confident Rainbow Dash we know.
One possible scenario could be that Rainbow Dash sacrifices herself to save Equestria from a powerful and evil force. Maybe she takes on a spell or a dangerous creature all by herself to protect her friends and the land she loves.
In a fanfiction, Rainbow Dash's brother could be an outcast among the ponies. He doesn't have the same level of confidence as Rainbow Dash and struggles to find his place. However, through a series of adventures and with the help of Rainbow Dash and her friends, he learns to embrace his own strengths and differences, and eventually becomes a respected member of the pony community.
Another scenario in a fanfiction could be that Rainbow Dash contracts a mysterious illness that no pony can cure. As she gets weaker, the ponies around her try their best to help. But in the end, she succumbs to the illness. Her death would cause the ponies to come together to find ways to prevent such a tragedy from happening again, perhaps leading to new medical discoveries in Equestria.
He could be a prodigy in a different area than Rainbow Dash. For instance, while she is great at flying stunts, he could be a master at creating flying devices. The plot could revolve around him creating a new type of flying machine that gets stolen by an evil force in Equestria, and Rainbow Dash and her friends have to help him get it back.
One great fanfic could be about Rainbow Dash taking Scootaloo on a special flying adventure. It might include Rainbow Dash teaching Scootaloo new flying techniques. This would strengthen their bond and show how much Scootaloo looks up to Rainbow Dash.
A great plot could involve a mystery on the farm. Rainbow Dash comes to help Applejack and they discover something strange going on. Maybe some of the animals are acting oddly or there are strange markings in the orchard. As they investigate together, their friendship grows stronger as they rely on each other's unique skills.