Responses
Maybe some drug or like energy boost
True
I'm just speculating BUT...
I think it's just plain water and they're messing with him.
Perez team has built up immunity from the dark energy and the first prince (can't be bothered to remember his name) is slowly going mad from the dark energy.
Ooh, that's possible too!
What's in that drink tho? Was it holy water or something, so the demonic energy don't affect them?