Barry would use his super - speed to take care of all the little things quickly. For example, if the reader has a craving in the middle of the night, he can zip to the store and back in no time. He would also be very protective, using his speed to keep her safe from any potential threats in Central City.
Yes, there are likely fanfictions out there with such a plot. 'The Flash' has a large and creative fanfiction community, and the idea of Barry and Caitlin having a pregnancy could be an interesting exploration of their relationship in the fan - created stories.
One idea could be that the reader discovers she's pregnant and is worried about how Barry will react. Given his life as The Flash, she might fear he won't have time for their family. Another could be that the pregnancy has some sort of meta - human related aspect to it. Maybe the baby shows signs of superpowers even before being born.
In a fanfiction about Barry and Caitlin being pregnant, it might explore how their powers interact with the pregnancy. For example, Barry's super - speed could potentially have an impact on the baby's development, or Caitlin's scientific knowledge could be used to ensure a healthy pregnancy. There could also be a lot of relationship - building moments. They might argue about things like baby names or how to raise the child. And of course, the Flash team would have to protect them from any threats that might come their way because of the baby.
One possible storyline could be them preparing for the baby. Barry might be worried about how his superhero life will affect the family, so he tries to make the city as safe as possible before the baby arrives. He could be seen training other speedsters to take over while he takes paternity leave. Iris, on the other hand, could be writing a series of articles about being a working mother in a world with superheroes, sharing her experiences and hopes for the future.
Another possibility is that Barry was kidnapped himself first and then forced to kidnap Supergirl. The real kidnappers could be a group of meta - humans who want to create chaos by pitting two of the most powerful heroes against each other. Barry would be in a difficult situation, having to do something against his will, and Supergirl would initially be confused and angry at Barry until they both figure out what's really going on.
Another theme is emotional pain. His relationships with friends, family, and love interests can be a source of hurt. For example, a broken friendship or a lost love.
Another theme is the importance of support. His friends like Cisco and Caitlin play crucial roles in helping him recover. They provide medical help, emotional support, and sometimes even give him the motivation to keep going in the face of pain.
In a fanfiction scenario where Barry is stabbed during a Flash - Supergirl crossover, it could lead to a lot of interesting plot developments. Maybe Supergirl would have to step up and use her powers in new ways to protect Central City in Barry's absence. She might have to team up with the other members of Team Flash more closely.
Power exploration is also a theme. Since the OC is often a new addition with unique powers, the fanfiction may explore how these powers work, how they can be controlled, and how they interact with Barry's speed - related abilities. This can lead to some really cool and creative plotlines.