Dennis Reynolds is a fictional character on the FX series It's Always Sunny in Philadelphia (2005–present), portrayed by Glenn Howerton, and created by Rob McElhenney, Howerton, and Charlie Day. He is the co-owner of Paddy's Pub, alongside his childhood friends Charlie Kelly and Mac. He is the twin brother of Dee Reynolds, legal son to Frank Reynolds, and is also roommates with Mac. He often plays the lead role in many of the gang's schemes. Overview Dennis is the twin brother of Dee and co-owner of Paddy's Pub. He has been friends with Mac and Charlie since childhood. The most amoral member of the group, Dennis is narcissistic, hypersexual, selfish, and abrasive. He is a graduate of the University of Pennsylvania and has shown to have extensive knowledge of psychology. Dennis has shown to be predatory towards women, as shown in a self-described system where he exploits women's trust and abuses them emotionally in order to have sex with them known as the D.E.N.N.I.S. system. Character biography Early life Dennis was born August 18, 1976, immediately after his twin sister Dee. He was raised by his mother Barbara and father Frank. In the Season 2 finale, "Dennis and Dee Get a New Dad", Dennis and Dee find out from their mother that they are the children of Bruce Mathis, a wealthy, kind-hearted philanthropist whom Barbara had an affair with. Dennis was beloved by his mother, who left him with her mansion after her death (on the condition that Frank would not be allowed to enter the property). He considered himself to be popular in high school, although it was later revealed that he was never that popular and that his prom date slept with Mac. Dennis graduated from the University of Pennsylvania with a minor in psychology and was a member of the Delta Omega Lambda fraternity. Personality Dennis displays signs of narcissistic, antisocial and borderline personality disorder, the latter of which he was diagnosed with and prescribed medicine for in "Psycho Pete Returns". Over the course of the series, Dennis's mental condition has significantly worsened, resulting in him becoming more delusional and deranged, even referring to himself as "The Golden God" on numerous occasions. Dennis also has an extremely fragile ego, as revealed through his upset reactions to being rejected by his peers at his high school reunion and receiving a one-star (and an eventual zero star) rating on