He came for the light. He stayed for the work.
One night, Hoolio noticed the workshop light was still on. He came in to see what was being built, found three unlabeled boxes and a pot of cold coffee, and stayed to straighten things out.
He has worked the late shift ever since: reading the notes, asking the useful question nobody wants to ask, checking the build, and carrying finished work to the door.
Nobody remembers giving him a key. The work keeps getting shipped, so nobody has asked.Read the character specification