Lieutenant Hugh Armitage

Lieutenant Hugh Armitage arrives in the Poldark circle as a wounded war hero, newly freed from a French prison and struggling with his eyesight. Gentle, poetic, and quietly persistent, he is drawn to Demelza Poldark, showering her with verses and soulful attention that unsettle the steadiness of her marriage.

Josh Whitehouse plays him as sincerity itself, which is what makes him dangerous rather than villainous — there's no scheming, just a wounded romantic who means every word. The show uses his poetry and fragile health to make longing feel tender instead of illicit, complicating easy loyalties without ever making him a cad.