The moment Rosso got through into the coffin, he really felt it was his end.
A certain end that he won't be coming back from, considering what he has done to Cynark. Death would be a mercy to him, and in case his captors were able to extract all the information that had been hidden in his head. Things won't turn for the better, as Rosso was aware of how the current world operated to some extent.
He would end up turning into research fodder or in the worst case, an enslaved death Knight for Cynark.
Though considered rumors or urban legends, among the world of commoners and most of the nobles, for certain people at the higher rung of society, the existence of Death Knights was not such a secret.
Mostly made up of Criminal Knights, they were forced to work for their Masters with their lives on the line. And there was no will behind their actions, they were barely capable of thought, and with the thought of their master, these Knights could easily die as well.
