His eyes fall half-closed as he's coaxed forward. Yes -- yes, all right, he knows what that means. Ford pulls Bill's lower lip into his mouth, then back out between his teeth, slow and deliberate. It's only a small bit of contact, but it's heated. His teeth are very close to the part of Bill that's least invulnerable, but he's inflicting deliberate pleasure, not injury. It feels more intimate than a lip-bite should.