Deanna was able to do all this, of course, because she exploited a crippling defect her victims have: their inability to communicate to one another. Not only have they pretty much walled themselves off from the world, they're virtual strangers to one another. Since the only things they discuss with one another are trivial things, nobody knows what the other family members want out of life, how they feel about things or (and this is most important) what they know about things. That means they don't compare notes to detect inconsistencies in other people's stories. When you combine that with a refusal to act on anything like a suspicion because they confuse befuddled inertia with fairness and an unjustifiable faith in their own skills as bullshit detectors, the result is a disaster. It therefore falls to others to live their lives for them. Remember Kortney and Eric? They'd both exploited the naivete of the Pattersons by shameless flattery that would send alarm bells ringing in the skulls of anyone with an ounce of self-awareness. In both cases, it took an outsider to handle the situation for them. The revelation of their incapacity didn't do Elly or Liz a damned bit of good, though. Instead of resolving to pay more attention to their surroundings, they retreated further into themselves. If things run true to form, some outsider will come barging in with proof so solid not even the Holy Community of Pattersaints cannot gainsay it that the poor, long-suffering martyr is actually a master deceiver who's turned every last one of them into a puppet in the service of her own warped ambitions. When that terrible day comes, they'll be fishing them all out of the Ravine of Death because they'l be so shattered, they'll have lost the will to live.