I'm not entirely sure without more specific information, but typically there would be a protagonist who is likely a subject in the Spiderhead facility. There may also be a figure in charge, like an overseer or scientist.
There could be a character who is trying to resist the system in the Spiderhead. Maybe this character starts to question the motives and actions of those in power and becomes the main focus in terms of the story's development. There might also be other characters who are more compliant, and their interactions with the resistant character can add depth to the story.