"Yes - but I was already his 'water brother,' just as you are now.  He has this crazy Martian idea that he can trust utterly anyone with whom he has shared a drink of water.  With a 'water brother' he is completely docile and with anybody else he is stubborn as a mule.  Ben couldn't have budged him." She added, "At least that is the way he was last week - he's changing awfully fast."