Charlie had been trapped in a dungeon pit for four years, where he was constantly drugged, raped and sprayed with a hose. On top of that, Charlie was forced to listen to Rose tell him all about how Alan carried on like he never existed and how Walden, a younger, richer and prettier individual, bought his Malibu beach house. That would be enough to drive anybody crazy. When he escaped, the now unstable Charlie had one thing on his mind - revenge. As for Evelyn, she had always been a terrible mother and Charlie's dangerous mindset was what pushed him from talking about killing his mother to actually attempting to do so.