Their relationship would go through a major transformation. They would start to see each other in a whole new light. Before, they were mainly focused on their love for each other and their superhero duties. But with a baby, they would become a family unit. There would be more shared responsibilities, and they would have to make sacrifices for the well - being of the baby. This would require a great deal of understanding and patience from both of them, which in turn would make their relationship more mature and complex.
Well, at first, they might be a bit nervous about how the baby will affect their relationship. But as time goes on, they would grow closer. They would have to communicate more about parenting decisions, which would strengthen their bond. Also, seeing each other as parents would add a new dimension of love. For example, Adrien seeing Marinette as the mother of his child would make him cherish her even more, and vice versa.
After getting married, they would become more open and trusting with each other. Since they know each other's identities as Ladybug and Chat Noir, there would be no more secrets between them. Their relationship would be more stable and they would support each other even more in their daily lives and superhero duties.
They would become even closer. Their love would grow deeper as they are about to start a family together. There would be more tender moments between them.
Their relationship would likely become more solid. Having a baby together means they are sharing a huge responsibility. They would have to depend on each other more, which would strengthen their bond.
If Adrien and Marinette were akumatized, their relationship would become very strained. As akumatized individuals, they would be full of negative emotions which could cloud their judgment. Adrien, who usually has a soft spot for Marinette, might not recognize her in his akumatized state and could even attack her. Marinette, too, would be in a different mental state and might see Adrien as an enemy, forgetting their previous friendship and any budding romantic feelings.
Their relationship could develop in a very interesting way. At first, Adrien might be completely lost in Marinette's world. But as he spends more time there, he starts to understand her better. He realizes how hard she works, how kind she is to her friends, and this new - found understanding could lead to him developing deeper feelings for her. It could start as a simple friendship based on this new - found respect, and then gradually turn into something more romantic.
Their relationship would probably become more complex. Adrien might feel a new sense of closeness to Marinette.
Adrien as a merman might become more in tune with the natural elements of the ocean. He could be more carefree and wild, as opposed to his somewhat reserved self on land. His love for adventure could be amplified, and he might be bolder in expressing his feelings, especially towards Marinette. Marinette as a mermaid could be more confident. The underwater world gives her a new sense of freedom, and she's less worried about the small things that bothered her on land. She might also be more assertive in her relationship with Adrien.
Well, it really depends on how the author writes it. If the overprotectiveness is written in a way that respects Marinette's agency, it could be a cute and endearing aspect of their relationship. But if it comes across as controlling, it might make Marinette resent Adrien, and then they would have to work through those issues to have a healthy relationship.
Adrien might become more protective. Usually, he's carefree to some extent, but with Marinette pregnant, he would be constantly on guard. For instance, he'd be extra vigilant against any potential threats, even the smallest ones. He may also become more serious about his responsibilities as a future father.
They would become more protective of each other. Since they now have a baby together, any threat to one of them would be seen as a threat to their family unit. Zuko might become even more determined to keep Katara safe, and Katara would do the same for Zuko. Their love would grow deeper as they share the joys and challenges of raising a child. They would also have to communicate more effectively, especially when it comes to making decisions about their baby's upbringing.