Dr. Gero is very coldhearted, willing to stop at nothing to achieve his goals, he doesn't let people get in his way and even kidnaps other people to use in his experiments. He also holds a strong hatred for Goku due to Goku defeating the entire Red Ribbon Army. He has the utmost confidence in his technological skills and intellect, as he believes, even when the odds are against him, that he, or his creations, will succeed somehow.