I know this is a comedy, but green anacondas are the least cold-tolerant giant snakes in the world. It would have made more sense if the snake were a Burmese python, which are more tolerant of cold temperatures.
The original soul is trapped while the reincarnate is in the driver's seat; the original soul really was as kind-hearted as she was in the original, the possessor, however, is a sociopathic b****.