"I don't imagine that the two being what I shall guess is roughly the same temperature is coincidence."

It can't be, not if the glass and the rabbit (or wolf or raven or whatever else these souls have manifested as) are connected. Given time and equipment, Alucard would suggest actually taking both temperatures and comparing them. Confirm the link. As it is, he can only sit and speculate, the heat in the fireplace now a bit too intense. He backs up carefully. Ellis moves with him.

"If they cool at roughly the same time..." then that's the connection confirmed, isn't it? But to say if is cruel.