It is a dream and maybe that's the one time he can allow himself that kind of freedom. It's a matter of self-control outside of this room but being back in the factory, even if it's just in his own mind, it brings him back to the days pre-soul, pre-Marina, pre-all this bollocks that've neutered him in every way imaginable. He could bite, here. He could drink his fill and do no harm.
For now he grunts, growls, presses his teeth against Jack's skin hard enough to leave a mark if not draw blood. The slow and steady falters, falls into a rough and erratic as he's starting to succumb to impatience. He grunts in frustration, breaking contact with Jack's neck just long enough to hiss out a:
"What's wrong with you Torchwood people and overdressing?"