Whether Hanz tells Vision in exquisite detail exactly how the sex is going to happen where, when and with what, or he just snaps his fingers and points to the ground, Vision gladly kneels and obeys because he can. Sex with Hanz, regardless of the leather and chains, doesn't change who Vision is or all that he has accomplished. If there was ever a point in his life that he was happy, this would be it.
But when the dreams come, the new threat from the grinning skull of the moon demands he sacrifice his happiness with Hanz in order to keep them both safe. He must sacrifice Hanz, or Hanz's son, to a rival vampire. Vision refuses to choose, even though it means entering back into sexual slavery himself. Now the chains and collars are real, and the only thing Vision has left to lose is himself.