Hmm, that won't work. Both have to very likeable for this to work, and this game is specifically about the relationship and choice between cynism vs. optimism, though it never takes a standpoint. The game is way too much built around this to change. When the choice is between "I must keep on it!" and "it's no use, I can't do it!" I see a better and worse attitude. I really need to prevent that for the concept to work at all.
Generally, how it works is that the fairies represent the main character and her opinions. However, they will focus on different things. Whenever the main character is in doubt about something, the fairies will polarize between the two sides of the main character's doubt.
An approach I'm trying to do right now is to make the optimist a bit too optimistic and enthusiastic, it seems to work.