So as I’m rereading Dracula and particularly this update (8/31) what really gets me is how the parallels and contrasts between Arthur Holmwood and Dracula as starting to become apparent. Spoilers under the bar, but:
Part of the reason why Arthur has been away from Lucy is because of his father’s own illness--- his father, Lord Godalming, who will die during the events of the novel. At Lord Godalming’s death, his title passes onto his son, Arthur, and so Arthur becomes a character who, like the other characters of Dracula, occupies a role in the various arguments of the novel, specifically power, wealth, and ethics.
Arthur’s place as a wealthy aristocrat already puts him in parallel to Dracula, but his decisions are what turns him into a true foil of the vampire; a light mirror to the problems of wealth, power, and corruption Dracula signifies. Count Dracula, the old, deathly, corrupt aristocrat who steals from civilians (not their money, maybe, but their life, their children, their blood) who lurks in the background of the second portion of the novel; Dracula, whose shadow is more often visible than himself (a bat in the air, a strange dog, Lucy’s intents night after night to reach the window, growing weaker and weaker,) except for one pivotal moment: when Mina sees him leaning over Lucy at Whitby Abbey. (And thus the plot of the second part of the novel redirects course.)
Arthur similarly is unseen, although not wreathed in shadow: little notes of Lucy’s correspondence, her missing him---just yesterday we found out he likes rowing and tennis! His reasons for absence are, of course, benign: his father’s sick and dying, and yet, the second he steps into the novel, with a letter to Seward, he similarly pivots the direction: he, without compromise, demands help for Lucy, even telling Seward to get over himself for Lucy’s sake. In one move, he does more to oppose Dracula than the other characters have been able to manage, because he ensures Lucy’s future help. Mina is able to help Lucy as long as she’s there, but she couldn’t call a doctor without alerting Mrs. Westenra; something which Arthur can do, because of his connections to Seward. In doing so, he will ultimately bring Van Helsing onto the scene, who is both able to treat Lucy, and who is the second half of the most vital duo in the novel in defeating Dracula (the first is, of course, Mina ❤--- seriously, the scene where they meet is the coolest moment.) His actions, then, taken to help Lucy, rather than hurt her, become further indicators of Arthur’s place as a foil to Dracula--- one who uses his wealth and power to help others, rather than hurt them.
tldr: Arthur and Dracula are both rich, powerful, and largely unseen, but Arthur is a force of good against Dracula’s evil, and his ability to counter Dracula is further evidence of their being foils.