This is lovely, anon :) So much domestic happiness. I love the idea that Finland's actually quite quiet when he's not filling in Sweden's silences, and the touches of magic from Norway, and the zombie metal, and the established-relationship non-drama of it all. It all feels very comfortable. Beautiful writing and great characters.

(Just one very small thing - whilst lowly is an adverb, it's slightly awkward and archaic, and is more often used to mean humble than to refer to a low voice/hum. I'd generally use words like softly, quietly and gently instead.)