Despite Leonard's reasonable and friendly personality, he occasionally demonstrates a mean streak. These include deliberately triggering Sheldon's obsessive compulsive problems, mocking Howard and Raj whenever they slip up, and making sniping comments when Penny's commitment issues flare up. He is also prone to jealousy, often feeling insecure and defensive whenever Penny interacts with other men, and on one occasion trying to frighten off a British college student she was doing a project with, because Penny commented positively on his accent. This incident ironically led to Penny finally, if inadvertently, declaring her love for Leonard.