So you take the blood out, then put it back in?

[ Trevor considers this, comparing it to the Many Belmont Methods for this kind of thing. ]

Could you just leave the blood where it was, and put the stone into the vein? Seems less dangerous that way.

[ Insofar as any of this is at all not-dangerous. It's also the same way that Those Fucking Silver Needles are meant to be used, but maybe not the best thing to bring up. ]