It's funny, I just finished a reread of 'Underneath the Shadows' last week. For me, the central figure is always the apothecary, Aris. The whole narrative is filtered through his quiet desperation and his meticulous observations of the village's slow unraveling. His notes, which we get as inter-chapters, are crucial; they make you feel like you're solving the mystery alongside him, sifting through botanical details and folk remedies for clues that are more human than herbal.
Then there's Elara, the newcomer whose arrival coincides with the strange blight. A lot of readers see her as the catalyst, but I think she's more of a mirror. Her past is shrouded, but her actions force the other characters to confront their own buried histories—the mayor's guilt over his brother's death, the schoolteacher's stifled ambitions. The key isn't so much a list of names, but understanding how Aris, Elara, and the mayor, Gerhold, form this tense triangle where secrets are the currency.