To predict how someone will act, it helps to know what drives them more: emotion or logic. Since the LazyTown characters are true to life in many ways, this idea could be fun to explore:
For example, Ziggy strikes me as the purest form of an emotional type. The clearest scene I can think of is when he throws his lollipop into a tree. He doesn't think things through and suffers the consequences.
Or Pixel is rather logical (or technological) but has tunnel vision w/ his designs. This way of working blinds him from seeing how his tech will affect people or be exploited by them.