Cloud's movements, Luki's movements-- they both fought for his over-sensitive attention, unable to move away without knocking Cloud over or hurting the girl more than he wanted to; so he simply braced his left arm, mechanical and fixable, allowing her to bite down (good teeth! she had to have been brushing them nightly) if only to distract himself with making sure that leg didn't hit him too hard-
Then Cloud went into play. Her teeth hadn't sunk deep, but they'd sunken enough, and he would've winced if he could've felt what his arm went through, tatters of red following Luki like a piece of cloth for a hound. He recoiled just as fast as he went forward, gunarm swinging behind him, ready to fire and. Pause. Vash stilled right beside the two, not willing to show either of them his expression (was Cloud getting through with Noki?), but all too willing to snap back into action at the first sign that talking really wouldn't help. He always had hope, after all. So the Stampede was stuck with is back against a wall, in a stance that made it obvious he could fire in just a few seconds- but waiting. Wait, wait, wait. Had to let the hope play out.