There are two words to describe unknown individuals. One is when it's under authority custody. The other is when it's really just some anonymous in the crowd. John Doe means he's a nobody. Mister X, means he's a somebody nobody's suppose to know about.
They are 2 robots.
John Doe dreams of becoming human. He's facinated about the way humans are able to understand eachothers emotions, smiles and the way they are tender to eachother. Every friendship, feeling and kindness.
Mr. X tries to warn John about humanitie's obscenity and that it's better for them to stay as far as they can from being anything like human beings, for they are ungrateful, vile, diseased and that at the same time they do understand their own sense of morals, they do not deny on breaking it or hurting other people if it's for personal gain.
One is the right side of the brain, the other is the left one~
John wants to be human, so he has those human parts around his pieces (It's up to interpretation wether they're real, plástic, silicone, whatever) and the more parts he gets, more humans run away from him, being increasingly frightened by his figure.
Mr.X on the other hand is just a pure machine.
No human fears him, since he is exactly what he seems to be, physicaly, simply what he is. A machine. When John notices people aren't afraid of Mr.X as they are of him, he gets angry and jealous of Mr.X and tries to destroy him.
"The thing that mostly makes you human is your will of self-destructing yourself without even noticing that all hardships you have, were, and will forever be your own creations." -Mr.X