In fanfiction, the relationship can be developed by exploring the contrast between Eyeless Jack's dark nature and the baby's innocence. The baby could unknowingly bring out a softer side of Jack. He might start to change his ways or at least show more restraint in his darker tendencies. As the baby grows and starts to understand more about Jack, they can have a unique and complex relationship that defies the expectations of their different natures.
The relationship can start with Eyeless Jack being initially curious about the baby reader. He might observe the baby from a distance at first. Then, as the baby shows signs of trust towards him, like reaching out or smiling, he could start to feel a sense of responsibility.
Eyeless Jack can be developed by showing his softer side when interacting with the baby girl. For example, he might be more patient and gentle, which is a contrast to his usual menacing reputation. This can add depth to his character.
They can develop their relationship through their shared care for the baby. For example, when the baby is sick, Elsa uses her powers to keep it cool while Jack tries to cheer it up. This mutual effort in taking care of the baby can bring them closer.
One interesting plot could be Eyeless Jack protecting the baby reader from other dangerous entities in the fictional world. Maybe the baby has some special power that Jack is drawn to and he feels compelled to keep it safe.
It can start with small moments of physical contact. For example, a brush of hands during a fight or while passing something. These small touches can gradually build up the sexual tension in a lemon - style relationship.
You could also develop their characters through their interactions with the environment in the fanfiction. If they are in a dark, haunted forest, how do they react? Jeff might be more fearless while Eyeless Jack might be more in tune with the spiritual side of the forest. Their different reactions can lead to discussions and arguments, which in turn helps in shaping their characters. Also, their reactions to other characters in the fanfiction world, whether they are friends or foes, can add depth to their personalities.
A good way to develop their relationship is by showing how they grow together. Maybe Samus teaches Baby Metroid some things about the universe, like how to recognize different types of energy or how to avoid certain traps. And Baby Metroid could teach Samus about the Metroid way of life, such as how they sense their surroundings. This exchange of knowledge and experiences would create a deep and unique relationship between them.
The relationship can start with Lucifer being both excited and terrified about becoming a father. He could be overprotective at times because of his newfound love for the baby. Chloe, on the other hand, would be more practical, teaching Lucifer about the normal aspects of raising a child. Their baby could be the center that brings them even closer together as they navigate through the joys and challenges of parenthood.
In the fanfiction, Uhura could be the main caregiver for the baby at first. As Spock observes her with the baby, he starts to feel a new kind of emotion towards both of them. He begins to participate more in the baby's care, like teaching it Vulcan meditation techniques. This way, their relationship grows gradually. Also, the baby could have a special connection with Spock due to his telepathic abilities, which further cements their relationship.
They can develop their relationship through shared experiences. For instance, taking the baby on a picnic in the forest and teaching it about nature. Arthur could show the baby how to fish, while Gwen tells it stories about the stars. Another way is through protecting the baby from threats. When danger looms, their parental instincts kick in, and they become closer as a family. Also, they can develop their relationship by celebrating the baby's milestones, like its first steps or first words, which would create precious memories for the family.
In many fanfics, Eyeless Jack and Nina the Killer can have a complex relationship. Sometimes it might be a dark, obsessive kind of relationship. Nina is often portrayed as being infatuated with Jack, while Jack may be either indifferent or have his own dark motives towards her. It all depends on how the author wants to develop their story.