Robdy (Robbie and Wendy)
While Robbie seems to be mean and condescending to everyone else, he actually seems to care for Wendy. Wendy fails (until Boyz Crazy) to see Robbie's true, lying nature.
Moments before Wendy breaks up with Robbie, Robbie tries one last-ditch effort to save their relationship. He says he lies about a lot of stuff, "like using your makeup and fighting a bear, although..." Which begs the questions: 1) Why was he using Wendy's makeup? and 2) What was he doing when he said he was fighting a bear, or what did he say he was doing when he was? It's also interesting to note that Gideon also steals Wendy's things (albeit her moisturizer instead of her makeup), and Manly Dan, Wendy's father, has been seen fighting a bear.
Robbie obviously didn't take their breakup well. As shown in Gideon Rises (and The Love God), he has apparently been relentlessly trying to win Wendy back since Boyz Crazy.
Other
I was a bit confused as to why Robbie ignored his "cold war" pact with Dipper... until Society of the Blind Eye. On a sidenote, they also managed at the same time to address a very common problem in TV shows: continuity errors, and specifically, monster-of-the-week storylines that are ignored in the rest of the series.
