Sir: Sebastian calls Jim ‘sir’ if he’s in trouble or reporting bad news or is extremely uncomfortable.
Boss: He calls Jim boss, mostly out of habit these days, but sometimes for reassurance. After the war, he didn’t like being in charge of people, and still now he needs the reassurance that someone is in charge of him.
Jim: Every day talk.
Jimmy: He started calling him Jimmy after Jim started calling him Sebby. When they’re messing around or if he’s worried about Jim, he’ll call him Jimmy.
James: He calls him James when annoyed with him or when trying to get his attention if he’s not listening or too distracted.
Kitten: It’s rare but he calls Jim Kitten every so often, sometimes teasingly, sometimes endearingly.