Through his short discussion with Trafalgar Law, Vergo proved himself to be a shrewd man due to his mistrust of Caesar Clown, having Monet placed on the island to monitor his actions. He can also come across as somewhat condescending, mocking Law's position by pretending to have some respect for the Shichibukai. Seeing himself as above the Shichibukai, Vergo quickly reminds Law of the difference in their power by beating him unconscious. He's also shown to be a person who demands respect from others, such as when he demanded that Law refer to him as Vergo-san.
Vergo stated that his favorite food is hamburgers. He appears to be a very messy eater, as he was first shown to have the hamburger still on the side of his cheek.
While around citizens, Vergo is said to be an amiable person, much unlike the other G-5 Marines. The parents of the children kept on Punk Hazard trusted Vergo's words that all of the missing children died in an accident. His statement caused them to partly believe that they were truly gone, though some parents still believe that their children are alive. Easily deceiving both citizens and the entire Marines organization, Vergo has proven himself to be highly manipulative.
Despite his perceived intelligence however, Vergo can at times seems to lapse into moments of air-headedness such as when he claimed to Caesar Clown that he had been enjoying coffee and cookies, only to be reminded shortly after that there had never been any cookies to begin with.