Jack blinks as the blade shatters, and he suddenly realizes that he should have expected this course of action. Maybe. It's rare for a friend of Jack's to not at least send him to his death, if not outright kill him with their own hands. (Currently, Martha Jones holds the prize for Jack's Best Friend on virtue of not killing him or getting him killed.)

Luffy grabs at his shirt, and Jack grabs at his wrist right back. The look in his eyes shakes some of the bravado, turns more desperate. "It's death that it wants, not life. It has to be me. You think two will do the job better than one? Then we do this together. Gamble that we get pulled back in time, come back with the others? Or that maybe one extra death is enough to satiate this thing's hunger?"

Jack leans in, looks Luffy strictly in the eyes, so close he's almost seeing double. "Two thousand years, alone, in the dark, suffocating, coming back to life, just to fear and suffer and die again and again and again. And it was for nothing. Worse than nothing, because I awoke just in time to see two of my friends killed. Let me do this. Let me make all of this worth something."

Jack's hand slides up, grips around Luffy's fist. "Together."