In Season 4, Episode 14, “Down the Rabbit Hole,” she landed on the Canadian island with her Elena (Nina Dobrev) costume in full effect. Then she used Jeremy’s (Steven R. McQueen) blood to awaken Silas, snatched the cure, and was gone before we could say “doppelganger.”
So why does Kat want that one dose so badly? By no means do we think the vamp wanted to bring Silas out of his dessicated state — it was just a means to an end. But she obviously went to great lengths to get the thing, risking her personal safety, which is not something Ms. Pierce often does.
This is just a guess, but we think she wants it for Klaus. Joseph Morgan told TV Guide that they have some unfinished business — 500 years worth. While she may not exactly run right back to Klaus’s clutches, they’ll likely come across each other sooner or later. Joseph says whether Kat is “trying to kill [Klaus] or make peace with him or trying to broker a deal with him” is still up in the air.
If the OV has been Katherine’s biggest fear for the past several centuries, it seems like dosing Klaus with some humanity would be the best bet for the doppelganger. Of course, that merely makes Klaus a werewolf — but it’s better than nothing!
Now, if the Bulgarian beauty can negotiate with Klaus, as Joseph suggested was a possibility, it remains to be seen what the Original would do with it. Ever in need of a hybrid army, he could give it to Elena (Nina Dobrev) — though we’re not sure she’d even want it anymore.
Then there’s Rebekah (Claire Holt), whom he told, “I hope you get to live and die as you wish.” Perhaps this cure will bring out his kindler, gentler side... even if he doesn’t take it himself.
Frankly, we’re hoping once Katherine realizes what she’s helped bring back to life — aka, Silas — she’ll forfeit the cure so the ancient witch can’t bring hell on earth. We’re with Kol (Nathaniel Buzolic): We like the earth just as it is.