An extended sneak peek of "How I Met Your Mother" is released for the first episode in the fifth season. The clip focuses on the three things that Barney has done with Robin, which he metaphorically describes as similar to keeping a Gremlin.
Fifth season will pick up right after the fourth season finale when Robin finally finds out Barney's love for her. When Marshall and the gang find out that Barney and Robin are hesitant to define their relationship, Lily forces them to confront their biggest fear.
Show's creator Carter Bays talked about the dynamic of Barney and Robin, saying "Well, it's not classic happily ever after, to say the least. It's two people that aren't programmed for happily ever after and never would have prioritized that, were it not for the fact that they're crazy about each other. So it's going to be a bumpy road for them. We'll have a lot of good stories. Now that things are out in the open for Barney and Robin, there's a lot of fun to be had."
Also in the September 21 episode called "Definitions", Ted is anxious about teaching his first lecture at Columbia.