Guiltythree
No one had to be manipulated. They are in an extremely dangerous place filled with nightmare creatures and could die any day. The lifestyle in the castle stopped being sustainable after new sleepers stopped being sent by the spell to the Forgotten Shore. Without Neph and Cassie doing anything, everyone there would die soon enough if nothing changes. They all understand that after having the harsh reality explained to them (not manipulation). The only chance the sleepers of the forgotten shore have at survival in the long term is to escape. Anyone who prevents that escape is indirectly killing everyone there. They have to try or die trying otherwise they just sit and wait to die.
Caio_Raeli:Nephis and Cassie manipulated them into doing it! And them lead them into killing everyone that disagrees with their plan.