David and Duncan both have been trained by ETs and by the human military, they are star warriors, and can operate in any environment, and they can work alone, or in tandem with other star warriors.
They have also been trained in ways other than either of the ETs and human military or intelligence have the knowledge to train them in this way or rather ways.
To protect themselves both the ETs and the human military or intelligence agencies have had the star warriors minds wiped, and blocked.
All star warriors have the ability to block this from being total, what they wiped and blocked was the false mind, each star warrior learned to create, if they were ever under guise to have their mind blocked or wiped, only the false mind would be wiped or blocked.
This is not to say the wipe or the block doesn’t work, because it does, but the false mind blocks any attempt to touch the star mind.
Duncan and Axe were paired off , not just so they could be a team, but to keep them tied to what they were right here and now. Pairing was done and is done, to keep the talents under control and tied to each other, so they wouldn’t go further into the training they’ve gotten, for then, they would be rogues, and would have to be hunted down.
The problem with that was/is the Godalarians, who would stop any attempt to kill, maim or mess with any of the Dragons, and they were Dragons, themselves.
A Dragon is a Dragon.