Mr. Swales plays a small role, but his interactions with Mina and Lucy seem to suggest a deeper significance. What is the significance of Mr. Swales, if any?
I had the thought that he was a sort of antithesis to Count Dracula: both dislike the idea of dying, but one of them accepts it as inevitable and the other doesn't. Kind of like how Renfield and Dracula both survive by devouring the life of beings weaker than them; Stoker used humans to show how Dracula has human-like characteristics, but is himself not a human. With the topics raised, and similar themes linked to those topics, the purpose of Swales is to act as Dracula's character foil alongside Renfield.
I'm only on chapter 7 though, so take everything I say with a grain of salt (if this is still useful, if not just ignore it).
"But I'm content, for [the Angel of Death is] comin' for me."
- Mr Swales, page 83
"[…]what he desires is to absorb as many lives as he can[…]"
- Dr Seward on Renfield, page 80