He might also feel a strange sense of protectiveness. Despite his often - villainous nature, the idea of a new life related to Elena could stir something in him. He could end up becoming an unexpected ally, ensuring Elena's safety during her pregnancy and protecting the child from other threats in the supernatural world.
Another possibility is that Klaus would be conflicted. On one hand, he has his own plans and power - hungry desires. On the other, the pregnancy could make him reevaluate his relationship with Elena and the whole Mystic Falls situation. He could struggle between his old ways and this new development that has the potential to change everything.
The pregnancy could bring them closer together. They'd be forced to rely on each other more. Klaus would protect Elena more fiercely, and Elena might start to understand Klaus better. For example, she could see the vulnerability behind his tough exterior as he worries about the future of their child. This could lead to a deeper emotional connection between them.
Klaus would likely become more complex. His tough exterior might soften as he anticipates fatherhood. He'd be more cautious and strategic to protect Elena and the unborn child. Elena, on the other hand, would grow from a somewhat naive girl to a strong woman. She'd have to face the harsh realities of being pregnant with a powerful vampire's child.
He might immediately hold the person gently and look into their eyes with a mix of surprise and love.
Well, one possible plot could be that Klaus and Elena initially have a very tumultuous relationship. Maybe they are forced to work together against a common enemy and during that time, their feelings change. Klaus might become more protective of Elena, and this newfound closeness leads to her getting pregnant. It could then explore how they deal with the pregnancy in a world full of supernatural drama and danger.
The other vampires in Mystic Falls who are against the idea of a hybrid - vampire baby could be antagonists. They might see it as a threat to their way of life.
Zuko could become extremely angry. If someone has intentionally hurt Katara, he would likely seek revenge. He has a strong sense of justice, and Katara is someone he cares about. So, he would not let the person who hurt her get away easily. For example, he might use his firebending skills to confront the perpetrator.
In some fanfictions, Edward might be initially shocked. He could be worried about Bella's health, considering the unique situation of a human - vampire pregnancy. He might also feel a sense of protectiveness towards Bella and the unborn child, and start making plans to ensure their safety.
Socially, it could be difficult for him. If others find out that he still has feelings for Lily and she's pregnant, he could face ridicule or be the subject of gossip. Also, depending on his relationship with Lily's partner, there could be conflict. He may have to face the fact that he has to keep his distance more than ever to avoid causing trouble for Lily and her unborn child.
Their relationship would likely become more complex. They would have to start thinking about their future together and as parents. There might be more moments of tenderness between them as they prepare for the baby.
One idea could be that Elena discovers she's pregnant and tries to keep it a secret from Klaus at first. But as the pregnancy progresses, she realizes she needs his help. Another could be that Klaus is initially angry but then becomes protective. Maybe there are threats from other supernatural beings because of the baby's unique heritage.