Desdemona Flood, or Dess for short, is a polymath. This means she is well versed and a genius with math. Her skill with numbers has not been seen anywhere else. She uses her ability to examine the latitude and longitude on maps to determine how extensive the blue time is. This helps her predict the changes that occur. She is also able to work with numbers easily in other ways, for example she can quickly identify thirteen letter words. This is a source of weaponry since these words serve as the names of tools the midnights use against the darklings and slithers. As a defense, her ability is only good during midnight but as an offense, she can use her knowledge during the day to prepare for the secret hour.
Dess has a hatred for Melissa because of her mindcasting ability. She thinks Melissa is manipulative. This tension is said to have started when Melissa stole information from Dess' mind. Dess constantly speaks out against Melissa. She refers to her as "the bitch goddess," both mentally and verbally. In the end though, she does acknowledge that her hatred towards Melissa is resolved.