The fact that our family knows a ritualistic way for hurting and temporarily thwarting this thing is what makes me wonder which one of its origin stories might be true. I don’t know how we know what we do—only that it was passed down by my mother to me and my sister Maggie, and now I’ve passed it down to you. Not because it’s easy or safe to do, but because it always seems to work when done correctly, if only for a time.

Whatever abilities that thing might have, it is physically limited to the body it is currently mimicking. That means it likely isn’t as strong if it comes at you as a child or as quick if it tries to throw you off with a sweet-looking little old lady. But it is relentless, clever, and driven with a clarity of purpose that allows for no hesitation or retreat. Once it attacks you, you either destroy it or it takes you.

Sometimes you may get lucky. Have enough forewarning or be able to escape long enough to set up some kind of trap or get a good weapon to kill it with that time. But most of the time it will be on you before you can do much other than react, and again, depending on the person it has replaced, it may be stronger or more agile than you.

So you do like I taught you. You don’t fight it. You aren’t fending off a mugger, and if you waste time fighting with it, you will lose. Instead, you just kill it. You stab your knife into all five of the ritual points: shoulder, shoulder, groin, stomach, heart, in that order. You do it faster than you think you can and perfect every time.

Like I always said, it comes down to knife control. You keep a small, fixed-blade knife on you at all times. All times. You practice knife control every day—fast motion and sure grip, and you only have to go an inch deep every time you hit. Shallower and it may not work, deeper and you’re wasting time and risking blade drag on the wound. You do not vacillate or hesitate. You look at the knife not as a tool or even a part of your hand. You look at it as an extension of your will to stay alive.

And if you do it right and you do it quick, it will be losing its grip after the first puncture. By the third it will be trying to get away. And after the fifth, it’ll just be gone, like it never was at all.

At least until it comes again.