To explain to Michelle and to himself why he was not acting his normal exuberant self, Ryan stated that while the others were busy talking, he was deliberately busy studying them, trying to classify them in his mind. He thought the others were probably thinking he was a quiet guy, but to him it was just a case of "the calm before the storm", where after familiarity set in he would let his personality explode and let the chips fall where they may.
Michelle agreed with him that he was not normally a quiet guy and that he wouldn't hold back once he got used to the others. Ryan was sure that that was true.
One thing that Ryan was specifically quiet about was his experience in the army. He was concerned that his fellow cast mates might stereotype him before they got to know the real Ryan. The biggest worry with that was that they would think since he had been in Iraq he had returned to civilian life with emotional problems. It's clear that that is something that Ryan does not want to be tagged with.
Ryan's hope: he wanted housemates to "get to know me for me."