One common theme is responsibility. The Akatsuki members, who are usually seen as tough and somewhat aloof, suddenly have to face the huge responsibility of being a father.
Another theme is the change in relationships. Their relationships with their comrades in Akatsuki can change because of this new role. For example, they might become more protective or more vulnerable, which affects how they interact with others in the group. And also, their relationship with the mother of the child (if she's in the story) is often explored. It could be a relationship filled with conflict, love, or a mix of both.
One common theme is the shock of discovery. The wrestler suddenly finds out they're a baby daddy, which throws their life into chaos. Another theme is responsibility. They have to figure out how to be a good father while still being a WWE star.
Love and family are also very common themes. Itachi may have been a cold - blooded ninja before, but as a baby daddy, he discovers the warmth of love and the importance of family. There's also the theme of secrecy. Given his situation, he has to keep the existence of his child a secret from many people, which adds a lot of tension to the story.
One common theme is redemption. Vergil, as a baby daddy, often has to make up for his past actions and become a better person for his child. Another theme is the struggle between his old life of fighting and his new role as a father.
Love and romance also play a big part. Often, the stories will start with them just being connected through the baby, but then they gradually fall in love. For example, in many fanfictions, Ben might realize how strong and amazing Riley is while they are dealing with a baby - related crisis, and that realization can spark his deeper feelings for her. It's a common trope in these stories.
One common theme is the protective relationship. The 'daddy' figure often protects the 'baby girl' from various troubles. For example, in some fanfictions set in a fantasy world, the daddy might be a powerful wizard protecting his baby girl from dark magic. Another theme could be growth and learning, where the baby girl learns important life lessons from the daddy. And sometimes, there is a strong emotional bond theme, showing deep love and affection between them that is not necessarily romantic but more of a family - like bond.
One common theme is the journey of self - discovery. Danny might be on a path to discover what kind of a father he can be, and Riley could be on her own journey of realizing her role in this new family - like situation. Another theme could be friendship. They start as friends, and the fanfiction might explore how that friendship is tested and strengthened by the addition of a baby. Love is also a theme, whether it's the love for the baby or a developing romantic love between Danny and Riley.
The theme of family is also prevalent. Even though they may not be related by blood, they form a family - like bond. Derek acts as a father figure, guiding and supporting Stiles. There's also the theme of loyalty. They stay loyal to each other through thick and thin in these fanfictions.
Family is a common theme. It could be about how Ben and Joshua deal with the situation of having a baby together or separately. Another theme might be love, like romantic love between them or with other characters in the story.
One common theme could be mentorship. The daddy bat could be seen as a mentor to the baby robin, guiding it in a world full of challenges. Another might be friendship across species. Despite their differences, they form a bond.
One common theme is protection. Blaine often takes on a protective role over Kurt, like a father figure. For example, in many stories he'll stand up for Kurt against bullies or difficult situations.