Over the years, the gang on It’s Always Sunny In Philadelphia have evolved in different ways. Charlie’s surprising ingenuity and illiteracy have become more prominent, Dee has tried to break off from her friends and get some independence, and Mac has begun to question everything he thinks he knows about himself, but Glenn Howerton’s Dennis Reynolds has just gotten more and more unsettling the longer the show goes on. He started as a fairly self-obsessed creep, but as seen in this supercut from a few years ago, he has gradually transformed into a straight-up sociopath who only cares about his friends when it suits his needs. In a sense, he has become the villain of the show.
A YouTuber named Ryan Hollinger thinks it goes a little further than that, though. He has put together a video presenting the fan theory that Dennis isn’t just a bad friend, but that he’s a serial killer. To do this, he lays out the kinds of profiling data that the FBI uses to identify serial killers, and—surprise, surprise—it lines up with Dennis pretty well. Granted, Dennis’ creepiness has been a long-running joke at this point, so it’s not really hard to make this connection, but it’s still an interesting theory (even if the video itself walks it back a little at the end). Of course, it’s hard to prove he’s a serial killer without the show doing an episode where he actually, you know, kills somebody, but that’s not the sort of thing that would generally happen on a comedy series.
You can see Hollinger’s video below: