Jillson is an Executive, rarely seen without her partner in crime, Jackson. She is a mean person and thinks that she is the best even though she really isn't. To prove it, she calls the Mysterious Benedict Society "little sqiurts". Jillson as an Executive obeys Mr. Ledroptha Curtain, and is a senior Executive. We have never learned her relation to Jackson. They may be brother and sister, boyfriend and girlfriend, or maybe just friends that met up in similar circumstances.