Many fanfictions focus on the character development of Connor and Markus through their relationship. They might start off with a lot of mistrust. For example, Connor might be suspicious of Markus' motives for starting the revolution. But over time, they could learn to respect each other. This could be shown through shared experiences, like facing a common enemy or making difficult decisions together. The fanfiction can take their relationship in many different directions, depending on the writer's interpretation of the game's world and characters.
In a fanfiction, a child Connor could be created by an error in the CyberLife system. He might end up in the care of Hank, who is initially very confused but gradually grows to protect him. The story could explore how Connor, in this child form, experiences emotions for the first time. He might be fascinated by simple things like rain or the feel of a pet's fur, which are new sensations for him.
There's also 'Connor's Uncharted Territory'. In this fanfic, Connor gets involved in a complex case that forces him to make decisions that go against his initial programming. It's really interesting to see how he evolves in this story. The character development is well - written and keeps you hooked.