In the Mirror Universe, circumstances and people were opposite to their regular counterparts. When Arnold Rimmer travelled to this parallel reality, he discovered that he was the ship's captain. In contrast, his low ranking personal assistant turned out to be Frank Hollister, who was captain in the original universe.
Hollister was an obsequious, conniving and ambitious but unlucky prisoner on probation. He was always trying to get on his captain's good side, bringing him hot lemon for his fever. He even tried to slip a free pardon into Rimmer's documents, so that he would sign it for Hollister. Rimmer spotted it instantly, since it was the same ploy he had tried on his own captain. Hollister desperately wanted to be an officer, but Rimmer took great pleasure in belittling him and called him "Private Nobody" and "Shambles". Rimmer ushered Hollister out of the sleeping quarters when Talia Garrett arrived. (RD: Only The Good...)
Behind the Scenes
The Mirror Hollister had a slightly longer scene with Rimmer that had to be cut down for the final edit. In it, Rimmer expanded on his ridicule of Hollister, making him repeat that he was a shambles.