Oh, Lucy. Lucy, Lucy, Lucy.
There are few characters in gothic horror, or fiction in general, that better exemplify the hell of being caught in a chronic state of highs and lows. I would jump straight to chronic illness--her battle with commandeered sleepwalking and vampiric exsanguination is very clearly that--but also the endless limbo state of one being preyed on by a stalker.
Right now, Dracula must be away, and so she's better for his lack of a new visit. His earth-boxes are being moved to their initial destination in Carfax Abbey, his respite in Whitby and toying with Lucy now paused. Lucy appears to be out of danger.
But she does not live in Whitby either. She must be on her way eventually. And even first-time readers can guess what's on the bleak and bloody horizon once she goes home.
It won't be a constant thing. A steep sudden drop and an ending. No.
Like sickness, like the menacing of a sadist who savors, Lucy's condition in Whitby has been a series of hills and valleys in wellness and ailment, joy and dread. The monster is jabbing a needle (two needles) into her over and over rather than skewering her in one go and being done with it. When he wants to collect a victim, he makes sure the uncomprehending fear, anxiety, and power play of the collection lasts.
More proof is to come on that front later. But Whitby's miseries are a great prelude. Highs, lows, hope, despair.