Carolyn has turned into a different person these days. Gone is the flighty adolescent, and suddenly she's a responsible young woman. I don't think this is altogether believable, but I would very much like to see Burke's response to the New Carolyn.
I see a giant internal change as having happened in Carolyn, triggered by Burke's rejection. It took place mostly off-camera, but then that's where internal changes happen, inside... She's smart enough, we could always tell by the entertaining sarcasm in conversations, but it had no organization or focus. She's only a teenager (?), after all.
She now appears to have had an epiphany that caused her to snap into focus, and form real priorities, beyond having a good time that evening. That shallow existence rested on the solid, dependable bedrock of Liz, her money, and power, and ability to handle everything thrown at her, and keep the dangerous world (which poor mortals have to deal with every day) at bay. The moment Liz became sick, weak, and vulnerable, far more vulnerable than Carolyn herself, that had to be an overwhelming sort of revelation, the kind that reorders ones internal world. That's two epiphanies at once... They're the same epiphany really, though, since her rethinking of Burke and Liz's illness both strike at the heart of her previously taken-for-granted security, her family's power. Burke and whoever did this to Liz both threaten it.
It's a little far-fetched, the sudden change in Carolyn, but then so many events in the real world do, until you find out the whole story. I
can say that Nancy Barrett plays it totally convincingly. I now enjoy witnessing the gears turning in her head.
When, by the way, did Elizabeth sign the papers putting Carolyn in charge in the event of her - that is, Elizabeth's - incapacitation? If it was after Elizabeth was taken ill, then Roger could claim that Elizabeth was of unsound mind at the time. And if it was before, then, all I can figure is that Liz hoped Joe would provide mature guidance for Carolyn.
You know, when those papers were prepared, Liz may have only had in mind some unforseen event that might happen years off, perhaps old-age-related, at a time when Carolyn would definitely have been of age. She may never have imagined herself getting ill soon, just as no one else seems to be have been able to imagine her becoming ill. (I've never met anyone who struck me as immune to illness, but then I've never made any connection in my mind between strength of will and the functioning of ones immune system.)
As for Carolyn being able legally to take charge as a teenager... frankly, I'm stumped. In real life, who would take over? Who is there? Would Roger's status as brother trump everything else?
... why is it so impossible - theoretically, I mean - that David should be responsible for Elizabeth's condition? He wants to be with his mother (conditions unspecified), which Elizabeth is opposing. He has contact with the supernatural, and we don't know what skills he might have acquired via that contact.
That's excellent thinking for living in Collinsport, Maine, and it comes from a veteran DS viewer. I think the answer is that Vicki, Guthrie et al have never seen Dark Shadows... To Dr. Guthrie's credit, I think he's trying to keep his mind open to any possibility from any direction, whether it comes from Vicki or not.