You might also explore Klaus x Elijah in a fanfic that delves into their brotherly bond and the power dynamics between them. There are many ways to create engaging fanfics without going into inappropriate territory.
Rather than this, you could look into more suitable pairings in fanfics, like Klaus with characters of appropriate age and nature. For example, Klaus paired with other adult characters from the same fictional universe can lead to interesting and ethical storylines.
One common theme is family. Since Klaus comes from a complex family in the Vampire Diaries universe, many fanfics about baby Klaus explore his family relationships. Another theme is his emerging powers. Writers often like to play with how his powers might have started to show when he was a baby.
One great 'baby Klaus fanfic' could be 'The Young Klaus's Adventure'. It shows a young Klaus exploring his powers in a rather innocent and endearing way. The story focuses on his relationships with his family members during his early years, painting a vivid picture of his character development.
One common theme could be family. Since they are likely related in the original context, exploring their family bonds in different ways can be a big part of the fanfic. Another might be friendship, showing how they become closer as friends despite any differences.
Redemption is also a theme. Klaus has done many bad things, and in some fanfics, Elena becomes a catalyst for his redemption. It shows how their relationship can change him for the better.
A common key element is the exploration of their unique personalities. Taki might be presented as more impulsive while Klaus as more reserved, and seeing how they interact because of these traits is important.
Klaus might be overjoyed. He has always been attracted to Caroline, and having a baby with her could be the ultimate sign of their connection. He would probably be very protective, using all his power and resources to keep her and the unborn baby safe.
Well, it could go either way. They could become closer as they both have a stake in the baby's future. Maybe they start to see each other in a new light, as co - fathers. But there's also a chance that their old rivalries resurface. For example, if there are decisions to be made about the baby's upbringing or training in the supernatural arts. Klaus might want to raise the baby to be more aggressive and powerful, while Elijah might prefer a more diplomatic and refined approach. This could lead to arguments and a strain on their relationship again.
You can start by looking on fanfiction websites like Archive of Our Own (AO3). It has a large collection of fanfics from various fandoms, and you're likely to find quite a few 'klaus x jeremy fanfic' there.