It could be her husband, Shining Armor. In the lore, they are in a relationship, so it's very likely that he would be the father. This would also bring in elements of their relationship and how they support each other during this time.
Shining Armor, her husband, would surely be a main character. He could be shown as a very supportive and protective partner. He might be by her side during doctor visits, making sure she is comfortable and taking care of all her needs.
One possible storyline could be Princess Cadence preparing for the arrival of her baby. She might be seen redecorating the nursery, choosing baby names, and sharing her pregnancy experiences with her friends and family. For example, she could have heart - to - heart talks with Twilight Sparkle about the joys and fears of motherhood.
A possible plot is that an old enemy tries to take advantage of her pregnancy. Maybe they think she's vulnerable in this state. However, Princess Cadence proves them wrong by using her inner strength and the support of her friends and family. Also, there could be a plot about her sharing her pregnancy experiences with other female characters in the kingdom, creating a bond among them.
In a fanfiction, Cadence's pregnancy could bring out different emotions. Shining Armor, her husband, would be overjoyed but also a bit nervous. Cadence herself might face some challenges. Maybe there are some old Crystal Pony traditions related to pregnancy that she has to follow. And the other ponies in Equestria would be sending their well - wishes and gifts from all over the land.
At first, they could be a bit wary of each other. Princess Cadence, coming from a more refined and magical background, might find Naruto's brash ninja ways a bit strange. But as they face challenges together, like fighting off common enemies or solving problems in their joined quests, they begin to understand and care for each other more. This could lead to a romantic relationship, with Naruto's determination and Princess Cadence's kindness complementing each other.
Friendship is a very common theme. Their strong bond as friends often drives the plot. For example, in many fanfictions, they support each other through tough times.
One possible plotline could be that Naruto is somehow transported to the world where Princess Cadence is from. Maybe he has to help her protect her kingdom from an unknown threat. He could use his ninja skills like shadow clones to confuse the enemies.
Perhaps Naruto is on a quest in an unknown land and stumbles upon Princess Cadence in distress. He helps her out, and she, in return, offers to help him on his journey. Along the way, they meet various characters from both universes. They learn from each other's values, like Naruto's never - give - up attitude inspiring Princess Cadence's people, and her grace and diplomatic skills helping Naruto in his interactions with different tribes in her land.
The plot could involve Cadence preparing for motherhood. She might have to deal with morning sickness and strange cravings, like eating only the rarest of crystals. Shining Armor would be by her side, constantly worried but also very excited. They could start decorating a nursery in the Crystal Castle with the help of their friends.