I think i remember from "The Flood" that she has control over his shields, cos she gets an infection form of his helmet by overcharging it - its killed by the discharge. Its logical to assume that she has more control, but i would guess that the suit's exoskeleton would work by responding in tandem using impulses taken locally from motor nerves or in the spinal cord, to cut down lag between the spartan's muscles and the exoskeleton, (a too large lag would result in a useless system) and therefore unless she can create impulses inside his nervous system, ie from bionics in his spinal cord, she doesn't have a lot of control over him. I'm not sure how effectively he can use the suit without power - I remember reading about updates to the MJOLNIR armour to remove the external, orbitally based power source cos it left the spartan in a hunk of dead metal, although im pretty sure even an average human could move in that much metal, unless there were motors deliberately counteracting movement... I wonder how an internal struggle would happen in terms of gameplay though - hopefully not a lame analogue-stick-waggling minigame... Apologies if i got a bit too serious/technical/nerdy there. I'm prone to it...