who is the free thinker who points montag in a new direction

That would be Clarisse McClellan. Guy Montag meets her as he walks home on a rainy night. Her questions are at first cryptic to Montag. At one point she asks if he is happy. Although seemingly simple, this question is very difficult for Montag to process. Clarisse is a free spirit; she tends not to ask how but why. This forces Montag to re-examine his own motivations for doing the things he does.