Alie's chip was taken from Lexa's body
the "commander chip" or the "Heda chip/soul" or ALIE 2
makes sense when you think about how Alie landed right after the war (the human)
her name was Rebecca Promheda--where the grounders get the "heda" title for their leader. they also got the "commander" title from the flight suit she was wearing
i hope we get even more backstory in s4. see how Becca managed to "tame" those ppl she did find and begin to get them organised in the midst of the after nuke war effects. And show just exactly how she managed to transfer-genetically-her 'commander's blood' (required to survive the commander chip install to the CNS) to grounders-or a part of them.
and that gives me a question i have been wondering about (and has been a part of a recurring theme in many post nuke apocalyptic films/shows):
we know the grounders are descendants of the survivors who were "exposed (vs ppl like those in the mountain who had no resilience to the rad effects because of their being underground)". and of course, the ark ppl have tolerance to rad levels because of their being born and raised in orbit.
so the science part--just how is it that some ppl on the ground did survive? it seems as though the ppl (the ones that Becca encountered) were in the remains of a city, pre-Polis city, and were also suffering heavy after effects and fallout,etc. So how is it, some ppl would have survived and others did not? Is the show suggesting that perhaps some humans are more genetically fit to survive such a war?
i am guessing that the writers-despite their good job so far-will just avoid this question
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I will assume that once you have read this you will be pretty much done with s3, so i won't be so worried about spoiling things