Spike and Tara- how does the chip know?

OK, so I saw the BTVS episode, “Family”, in which Tara’s father, brother and cousin come to take her home, claiming she’s part demon, and will change into something nonspecifically nasty on her twentieth birthday.

Of course, Anya brings up the logical question, what kind of demon is she? While the fam is hemming, hawing, and asking if it really makes a difference, a demon’s a demon, Spike decides to “simplify matters a bit” by punching Tara in the face, causing himself intense cerebral pain and proving Tara to be fully human.

OK, so how does the chip know? I mean, until that episode, Spike had no reason to think Tara was anything other than human, and didn’t seem to be buying the fam’s story. Suppose Spike had been convinced she was a demon, even though she wasn’t, would the chip have been triggered? Or, if she had been a demon, and Spike thought she was human, would the chip do its little chip thing?

I want to know where the chip gets its information from. Seems that it doesn’t have any external sensing device, aside from Spike’s eyes, ears, and skin to tell it what he’s fixing to tango with.

Er, I suppose the answer you want to hear is not “The chip knows because it’s a plot device,” is it?

Well, the only other thing I can think of is that it’s some super high tech chip designed by the government for the brains of vampires. Who says it couldn’t somehow scan the DNA of the people near it or something? I mean, as long as it’s fictional, it can do anything.

HSTs left specific protien markers that the Initiative used to track them… it is, in theory, possible that the chip operates on just such a principle. I don’t believe it was ever stated for certain.

Writer’s magic.

Well, remember when Buffy goes to Tara because she wants Tara to do research to find out “how she came back wrong” from the dead because Spike can hurt her.

I forget the exact mumbo jumbo that Tara said, but basically Buffy was changed at some very deep level and the chip no longer saw her as a basic human.

So, the chip knows.

?

Heh.

I’m pretty sure she described it as a “deep tropical cellular tan.” But they dodged the question about how the chip works, because Tara says that whatever happened, it was “just enough to confuse the sensors or whatever in Spike’s chip.”

Deus ex machina

and buffy did, for all intents and purposes, die.

spike can beat up on dead things. apparently, the chip equates a death with being dead, so buffy’s fair game.

Umm, well, no, I haven’t actually seen that episode, waiting for the summer rerun.