When Jack first gets his tattoo, he wants to touch it constantly. It seems obscene, somehow, like masturbating in public. He can't help that what he feels for it projects. You only have to look at him once to see the reverence, the need, the erotic thrill that threatens to consume him. It's the kind of feeling that shines out from the faces of saints and martyrs, and all other pure narcissists. He looks like St. Sebastian, or Christ on the Cross, or Mary from the PietÃ .
And he understands that it confuses people, that when they see his tattoo they're not sure exactly what to think. He's a doctor with ink, a surgeon who let himself be poked and prodded with needles. A white hat with a dark stain. His tattoo is absolution in desecration. It blots him out, taints him, a stain only in the periphery. He needs that. Jack never wanted to be perfect. He never wanted to be a doctor, or a hero, or a leader. He needs to mar perfection, and pretend its perfect anyway.
He needs it more than ever here. The jungle is dangerous, but worse, it's portent. It knows Jack. It recognizes him. And Jack understands it in a way he's only understood once before - in Phuket, in a small dingy room where a man with numbers tattooed down his back inked Jack's arm. You know, sometimes Jack wants nothing more than to disappear inside the jungle. Assimilate. Become. He wants it, and he's afraid of it. He has to be. Because whenever he feels like dropping all responsibility and running towards it with open arms, he thumbs his tattoo and reminds himself that it'll keep, that there's enough darkness in him all ready.