Every fantasy world has a character who is there to show that there's a range of personalities among the principle characters. The easiest way to show this is to make him annoying. This goes double for when a fantasy is made into a movie, where this character is often portrayed as short with a high nasal voice. You can spot them a mile away. They may be heroic or villainous, or only brought in for comic relief, or they may end up having the key to the entire conflict. Alasdair Beckett-King, the man with the reddest hair on YouTube (previously at Neatorama), illustrates this in a hurry in a very short film, even managing to mention examples along the way. You can write reams about this trope, but if you've seen a few fantasy films, you'll already know what he's talking about. Here he gets a lesson in judging people merely by their annoyance level, because that's relative.