Often, when there's a superhero team, their powers will reflect their personalities with the most blatant symbolism possible. Somebody with sun or light-based powers will be optimistic and sunny, while somebody with moon or night-based powers will be moody and dark. This can, of course, be a chicken/egg thing. If a person has a set of abilities long enough, it can influence their personality. In other cases, their personality is what influences the powers they get.