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.
I'm not sure which specific 'five x klaus fanfic' you might like. But you can try searching on fanfic platforms like Archive of Our Own. There are often a variety of stories based on different pairings, and you might find some really interesting ones there.
Klaus may be overjoyed. Given his complex character, he might see this as a new beginning, a chance to create a family of his own in a way he never thought possible. He could immediately start making plans to ensure Caroline and the baby are well - cared - for.
Klaus might be initially shocked. He's used to a life of danger and chaos, and a pregnancy would be a huge change. But then he would become very protective. He has a complex personality, but deep down he cares about Cami, so he'd do everything in his power to keep her and the unborn baby safe.
In the comics, Klaus is not immortal. He may have certain powers and abilities, but there are limitations and factors that can pose a threat to his existence.
In some comic versions, Klaus is indeed depicted as gay, with storylines exploring his romantic relationships with same-sex characters. However, this can vary depending on the creative team and the direction of the story.
Klaus isn't gay in the comic. The creators have not developed his character along those lines. The focus of his portrayal lies elsewhere in the narrative.
Klaus is not based on real events. It's a work of imagination that brings together various fictional characters and plotlines to form an enchanting narrative.