After that night on seeing Cesar continuously pouring out blood from his holes which continued to happen for a few minutes, Arnold changed his stance when dealing with The Freak of the Academy.
What happened to him there wasn't normal after all.
Besides, some of the reports that those interrogated from the Library saw him doing the same thing after battling away a Nightmare that had disappeared.
Arnold didn't know that Cesar had suffered like that. After all, the results of the examination of the condition while he was unconscious all told him that he was all right.
There weren't any major injuries suffered from him nor was his mental or emotional state in disarray.
But it didn't look like he was suffering from any illness yet Arnold knew Cesar was keeping his condition to himself while feeling crap on the inside.