"I watched one movie, but I'm not sure if it's American or Canadian. I can't even remember what the name of it was, but it had to do with the legend of the Winnebago monster or something (no not the RV) and two sisters. One sister gets infected by this monster and the indian guy keeps telling the other sister that she was going to have to end up killing the infected sister because she'll turn on her, but in the end the uninfected sister ends up killing the indian guy and freeing her infected sister, who unleases the curse of the winnebago on the outpost they were seeking shelter in.
I remember the ending where both sisters are out sitting in the snow, the infected one stroking the other's hair and the unifected one says "I'm cold." and the infected sisters like, "I'm not." so, yeah. Something about the bonds of sisterhood that can't be broken, that's why they wouldn't kill each other."