Both what "Durkula" says to the world and what he says in internal conversations.
This even includes the few bubbles "Durkula" said when he was still a thrall to Malack, since I don't think that there is a difference between thrall-Durkula and Hippo - only that the thrall didn't have free will yet.
PS, I will also include the count of him as Hel's mouthpiece during the voting, unless the goddess speaks directly through the summon proxy spell.