Jonathan is a security unit at the northern installation, he's primarily responsible for the doctors' safety when moving between residences.

He's pretty diligent to his work and takes it as the main part of his life, he has a couple side hobbies like robotics, but not much time is spent on them.

At the start of the story he loses his left forearm, making a prothesis for himself later on. When Pratz loses his right arm he makes a matching one for him, with a notable difference in quality from his own.