The eye tattooed on Carl's chest, still aching in the zero zone after Faction Wars.
When Carl comes out of Faction Wars into the Zero Zone, he takes inventory of his body without meaning to: feet tingling with waking-up-from-sleep pain, his entire body aching, and the eye on his chest aching with it.
It is one detail in a short list, and it lands harder for being undramatic. Covered in ash and blood, shaking, leaving black handprints on the table, Carl notices the eye hurting the way he notices everything else that is still attached to him and still costing him something.
A large eye tattooed across Carl's sternum, aching in the aftermath of the war.
A marked reminder, still hurting, of what Carl carries out of the tenth floor.