Dennis Reynolds is a co-owner of Paddy's Pub in south Philadelphia, along with his best friend Mac (who is also his roommate) and his father Frank. Dennis' sister Dee also works at the bar, as does his childhood friend, Charlie.Dennis has a way with the ladies and his good looks and charm often get him what he wants. He is afflicted with narcissistic personality disorder. Dennis is surprised when things don't go his way. He developed the D.E.N.N.I.S. System for sleeping with and then getting rid of women. He video and audio records his room 24 hours a day, seven days a week, and therefore has a vast collection of recordings of himself having sex with various women.Dennis also may be anorexic. He often refers to having been popular in high school and has never truly broken out of that popular-guy mentality. He also attended the University of Pennsylvania and claims to have run the fraternity he was in there. Dennis minored in psychology and has developed psychological dossiers on each member of the gang. He started one on his sister when they were in the second grade.Dennis is incredibly lazy, always looking to get the most reward for the least amount of exerted energy. He, along with his sister Dee, once became addicted to crack in order to qualify as a recovering drug addict and get welfare benefits.Dennis' inability to empathize leads to some often alarming suggestions and references to psychopathic behavior. He has also done much physical damage to other people's property.