'Higher Nightmare Creature!'
If that was already enough to understand how the situation unfolded, Cesar realized right away that their decline was related to the Nightmare. For it to remain alive until now, means it is a Higher Nightmare Creature that is widely known to all.
Cesar hadn't even met such a creature of that caliber yet but he came to know one of them. It was the creature under the table that became Dwellers of the Dark, the very same Nightmare that corrupted Erin.
He remembered it was Cedeit who informed him of the creature hiding under the table, and that Cesar was lucky to not be able to meet it or he would've suffered the same outcome as Erin.
'Sir Erin…'
Now that he was thinking about the soldier who sacrificed himself for others at the table, Cesar wanted to see the burial they did for him and the others whose lives vanished the moment they started exploring the Mansion.
It was just a basic courtesy to do, and rightfully so.
