Why tell when I can just show you? [ Stefan stops walking and waits until he has her full attention before he tugs down the collar of his t-shirt low enough to reveal the x-shaped mark that's carved deep into his skin, right over his heart.

The wound doesn't appear as fresh as it once did, presumably because Rayna isn't actually here in Wayward Pines by some small miracle. But the fact that there's a wound at all should be pretty alarming to a fellow vampire like Katherine. ]

She's an immortal huntress who stabbed me her magical sword. This is her mark. It allows her to track me down to the end's of the earth; no matter how far or how fast I go, she will find me if I ever stop running. My only choice has been to stay constantly on the move.