I wonder if she acts stupid in that she's battling the monster inside her and that takes up all her focus, or the carefree "baka" cirno is just a front because she doesn't want her demons to take over. -shrugs-
Well Cirno is the personification of the cold. And the cold is actually quite a grim thing if you think about it. Grimmer than the darkness. Heat/energy is essentially required for life, any life. Cold is not essentially a thing, but a lack of a thing that being life. Meaning that the cold is the lack of life A.K.A death. The colder you are the closer you are to eventually being dead. She personifies what is going to end our universe if we don't find a way to stop it. Entropy/Heat Death. War could be considered an entropy of sorts on human life. Any death is a case of entropy on your entire body. Entropy affects practically everything. Her very existence abores life.
