There's no evidence to suggest that Katherine Barrell reads fanfiction. Fanfiction is a bit of a niche area and not all actors engage with it. It could be that she's never even been exposed to it or she might be into it privately, but without any statement from her or her team, we can't really know.
A common theme is the struggle for power. Since both are strong - willed characters, many fanfictions explore who is more powerful or how they vie for power in different situations.
There are quite a few. Since Elena and Katherine are such iconic characters in the Vampire Diaries universe, fans often like to create their own stories about them. Some fanfiction might focus on a romantic relationship between them, while others could explore how they interact in different scenarios than in the show.
Another theme is power struggle. Since both Elena and Katherine have their own strengths and agendas, a lot of fanfictions play around with who has the upper hand in different situations. For example, in some stories, it might be about Katherine trying to outwit Elena in a battle of wits. And in others, it could be Elena using her newfound powers to stand up to Katherine.
There's a fanfiction called 'Katherine's Redemption in Elena's World'. In this story, Katherine tries to make amends for her past wrongs towards Elena. It's a fascinating take as it shows a different side of Katherine that we don't often see in the original series. It also has a great plotline that keeps you hooked from start to finish.
A common theme is power dynamics. Given that Katherine is often portrayed as more powerful and manipulative compared to Elena, fanfiction may explore how this affects their relationship when love is involved. Also, the theme of identity and how they see themselves in relation to each other through love is popular.
Caroline would likely be a mix of excited and cautious. She's a bit of a romantic at heart, so she might see the potential for a new family dynamic. However, she also knows Katherine's past and would be on guard to make sure Katherine doesn't manipulate Damon during the pregnancy. She would probably try to befriend Katherine to keep an eye on things.
In Klaus and Katherine baby fanfiction, it could be interesting if the baby was born with a prophecy attached to it. The prophecy might say that the baby will either bring great peace or great destruction to the vampire world. This would put a lot of pressure on Klaus and Katherine to ensure the baby grows up to be a force for good. The baby might also have an unusual appearance, a blend of Klaus and Katherine's features, which could make it stand out among other supernaturals. And as the baby develops, it could start to show signs of having a moral compass that is different from both its parents, leading to some interesting family dynamics.