Clavis

Clavis runs the elevator that carries arbiters and guests between the tower's floors, always smiling and rarely opening his eyes as he works. Underneath the easy manner is someone genuinely trusted with sensitive information — he's one of the few people who knows that Decim has been given human emotions, and he keeps that secret without complaint.

He is fiercely loyal to Nona, serving as her closest aide and ferrying her wherever she needs to go, and he treats Decim with the same easy politeness he extends to almost everyone. His relationship with fellow arbiter Ginti is more complicated, mixing teasing with real concern, and he stays close to Ginti even after the disappearance of Ginti's companion, a cat named Memine.

When suspicion falls on Nona's experiment, Clavis has his own memories read by the tower's overseer and is dismissed just as quickly, left unaware of what was actually found. His name, drawn from the Latin word for "key," fits a character who literally holds the means of moving between the story's floors.