It's Always Sunny In Philadelphia: This Theory About The Waitress Will Blow Your Mind
4. The Waitress And Dee's Eerie Similarities
The question remains, however, how has Charlie's misplaced his affections for Dee manifested itself into an obsession with The Waitress? Well, the show regularly highlights Charlie's dyslexia, is it too far-fetched to imagine he gets his emotions mixed up as well? Furthermore, in The Gang Gets Analysed it shows that he has very little grasp on his own emotions let alone how to express them.
Charlie's mix-up between the two isn't all that far fetched because, if you look at it, the two of them are eerily similar:
In High School, they sat next to each other in Trig and both dated Brad Fischer (the origin of Charlie's confusion), they both worked at the same restaurant (season 2 episode 4) at the same time, they both have blond hair, they both have problems with alcoholism (and if you watch carefully, they act almost identically when drunk, even their drunken mannerisms. Sure there isn't much range in drunk acting but it feels intentional), but, most importantly: they are both waitresses.
The fact they are both waitresses means Charlie can openly say he loves "The Waitress" without having to specifically say which waitress he loves. That way, his love for Dee can remain in his subconscious.