Caesar is the Graystone family's dog. He is the puppy of Daniel Graystone's previous dog. He is allowed in Daniel's lab and appeared to sense that there is a sentience in the U-87 robot (CAP: "The Imperfections of Memory"). In an attempt to convince the U-87 to identify itself as an avatar of his daughter Zoe, Daniel gives the robot a handgun and orders it to shoot Caesar. It complies, but the gun is loaded with blanks, sparing the dog. Zoe is aware of this because her Centurion body could sense the gun's weight is too low to be filled with real bullets; otherwise, she might have turned it on Daniel (CAP: "Ghosts in the Machine").
- As stated in Serge's twitter account