This goes in the column of things I thought everybody just knew.
But I got this question the other day about why Lydia didn't react to the venom
of a kanima in the appropriately titled season 2 episode Venomous.
This all started as a Derek Hale big brain plan
to discover which of the sexy teens had gone all lizard king.
Derek says to himself one day, "Self, I bet you if we fed kanima venom to the folks who I think
might be the kanima, they'll be immune like a snake is immune to its own bite."
He then patted himself on the back and brooded an
extra five minutes in the mirror as a reward for his excellent thinking.
Derek: You know Jackson, you've always been kind of a snake.
And everyone knows a snake can't be poisoned by its own venom.
So Derek kidnaps one sexy teen and force feeds it the paralytic venom and it does
exactly what it says on the tin - it paralyzes the tested teen.
"Well," Derek thinks in his big brain, "the venom worked. So this is not the sexy
teen we're looking for.
Maybe it's this one over here, the smart one.
Aha! She ate the chemistry class rock candy and didn't get paralyzed. Ipso factoid,
she must be the secret lizard!"
Derek: She failed the test.
Scott: Yeah, which doesn't prove anything. Lydia's different.
Derek: I know. At night she turns into a homicidal walking snake.
Just a quick side note here, something I realized
while recording this is that Derek doesn't actually get smart until
after his brains and body get scrambled in Kate's Temple tomb down in Mexico.
Up until that point in season four,
he really is just kind of stumbling around making a series of bad decisions.
Deaton: Don't worry, you're still an alpha. But, as usual, not a particularly competent one.
How dare you!?
You suck!
Why do you hurt me?
Anyway back to season two.
Derek: She failed the test.
Derek thinks his little science experiment is "beyond a reasonable
doubt" death penalty-level proof that Lydia is the kanima.
Those of us watching know that is not the case
because we have been paying a little bit of attention to the show so far.
Scott: What if she's immune? What if she's got something inside of
her that makes her immune to the bite which is why she didn't get paralyzed?
Derek: No one's immune. I've never seen it or heard of it.
At this point in the story we're not 100 sure what Lydia's deal is,
but we know she's not affected by Peter's bite.
It made a wound which healed normally without a hint of any supernatural shenanigans - physically.
Physically it was like any normal dog bite.
So we already witnessed that one of the most transformative things in this universe - the
bite of an alpha werewolf - had zero physical effect on Lydia.
We can probably extrapolate from that fact that a little venom from a malformed
werewolf isn't going to do anything either.
This is a perk of Lydia's Banshee lineage.
They are humans who can touch the supernatural world but they're not
a part of it and they cannot be physically changed by it.
That is not to say that a kanima or something else can't hurt Lydia - like I said Peter's
bite was painful and probably infected and it came with a number of mental side effects.
And while a kanima's venom won't paralyze Lydia a deep stab with
kanima claws can certainly nick an artery and cause her to bleed out.