Their relationship would likely become more complex. Klaus, who is used to being in control, might become more possessive yet also more tender towards Elena. Elena, on her part, would have to rely on Klaus more, which could create a strange bond between them. They would have to learn to trust each other in a whole new way as they are now responsible for the unborn child.
The relationship between Elena and Klaus during her pregnancy would be full of contradictions. On one hand, Klaus's protective instincts would kick in, and he would do everything to keep Elena and the baby safe. This might include going against his own nature and making peace with his enemies. Elena, on the other hand, would be dealing with the fact that she is carrying the child of someone she once considered a great enemy. She would be torn between her feelings for Klaus and her loyalty to her friends. There would be moments of tenderness, like when Klaus feels the baby kick for the first time, but also moments of conflict, especially when their different worlds collide. Their relationship would be a constant struggle between love, hate, and the shared responsibility of the unborn baby.
During the pregnancy, their relationship could go through a major transformation. Klaus may start to see Elena in a new light, not just as someone he desires but as the mother of his child. This could lead to him being more selfless and putting her needs first. Elena might initially be hesitant and even resentful, but as the pregnancy progresses, she could start to understand Klaus better. There would be a lot of communication and negotiation as they navigate the changes in their relationship, both emotional and practical. For example, Klaus would want to ensure her safety at all costs, and Elena would have to accept his over - protectiveness to some extent.