Passive leading

We're coming into a tricky business. The laws of tango say that leader leads and follower follows. Surely, in (proper) tango, at any time, the leader should be the one that ultimately decides what to do with the movement. Not only the embrace is structured in a way that the leader has that power (the right arm below the follower's left axilla, to ensure the most efficient energy transfer) but also the leader has an angle of vision that the follower doesn't. These and other make the role of leading very clear.
But like many civil laws, there is a loophole in the law of leading. Nothing stops the follower to suggest the leader a certain movement, provided that (1) the follower can actually be subtle enough to do so, (2) the leader has the receptivity to it and (3) that the follower has strong navigational cues and knows where the movement is going.
This has been taught to me since I became a post-intermediate by my teachers in Edinburgh, Ricardo Oria and Jenny Frances (they did teach me this since the beginning, but they waited until I matured enough to actively make me do it). But the moment when it clicked was when I had my first workshop with the great Rodolfo y Gloria Dinzel. Rodolfo has an incredible charisma and Gloria has an aura of glow that you will attract you like a magnet. What they say sticks to your mind, whether you like them or not (I learnt that they elicit as much passion as hate). The idea is that if tango wants to be a true communication between partners, then the message should go both ways. The connection between the follower and the leader should be the one that, provided that the three criteria above mentioned are fullfiled, it allows both partners to have an active role.
Let's imagine a simple situation illustrated by mshedgehog that tells us about the simplest form of passive leading. The guy is going to step back, the lady sees somebody stepping into the place he is going to step and exerts a small pressure on his back. This should tell the leader that he should not take that step. But if the follower is quite good at passive leading, she might even lead him to do another step, maybe a giro or a walk forwards, avoiding the disruption of the sudden change of movement. From here onwards, the concept of passive leading can extend to the point that the whole dance is a constant flow and backflow of leading and following. Both partners become leaders and both become followers... Instead of the unilateral dialogue with the pauses so that the other partner can finish the sentence, a dialogue in which the words travel smoothly from mouth to mouth.