[ There's a difficulty to it, doing this when Alucard is so ill at ease with it. Trevor is molding his intent, putting real power behind it. But the only reason this can work without vampiric blood is that Alucard is, at least theoretically, willing to allow this. The moment that his intention turns to getting Trevor out of his body, the spell will be broken. ]

I'll let you walk there yourself. Speak when you're ready. I'll hear you. And take the skin. Now we've found her, I can use the last of that spell to test that we can counter it.