Pandora assimilated Jake. None of the other Avatars were that involved with the local population, not even Cage. Sure, they were intrigued by it and wanted to establish good relationships, but Jake was the only one who went far. Why was that? Especially when he was pleased with his old life, and was going to get his legs back? But it was hinted at in the movie that he was the first Avatar to actually use that neuro-upload thing, or at least repeatedly.
What if the planet used him, began overwriting his human self, so that it would have a weapon against those invading it's "body"? It was quite easy after all: A "pure" heart is the easiest to 'corrupt', and his disability made it even easier for him to get 'lost'. Then, at the end, he is 'rewarded' by having his human self killed so that the planet can upload his memories and personality into his Avatar form, since it was already said that they only upload memories, not their actual souls.
As for the others; well, it was easy for them to be manipulated as well thanks to their involvement with Jake. Maybe Quadritch either knew or suspected all of this as well, having been on the planet for so long and having seen how hostile it is, and he is certainly not a foolish man.
. I hope they'll exchange them when I phone the imax.
I just booked the latest possible incase I feel like crap for the next week.
