[So useful that his blood is cleaning out his wounds for him. Guess there's an upside to nearly bleeding to death after all.
Ciel's fascinated by the split in Sebastian's shoulder as he gets near, never having seen the aftermath of The Ripper incident when that ridiculous grim reaper had shoved his death scythe into Sebastian's shoulder. Is this what it would have looked like, minus the surrounding chew marks? Sebastian never allowed Ciel to see his wounds. Of course, the next pulse of blood flowing out pretty much kills that fascination in its track. Disgusting.
But yes, all right, drug the person before you stab them, got it.
Ciel fetches the bottle of alcohol out of the kit and without an ounce of moderation, steps in close and pours a quarter of the thing on Sebastian's wound.]