as thwurp told the story of king lars life , grendel had , at first , asked many questions and had sought clarifications and explanations of things that thwurp had told him , but , as the catalogue of battles , sieges , killings and lootings mounted he had become progressively quieter , until the only voice was thwurps and this eventually droned to a halt after the building of the beer hall and the taking of the royal dog .