Water!

Knowing that, if Aiden maintains this rate of recovery, he should wake up anytime within the next twenty-four hours, Dr Robert still kept mute and went about his duties without saying a word to anyone. 

He just wanted to monitor Aiden and make sure that everything was okay before he gets anyone's hopes up. He finally decided to rest, after planning with Calvin on how to let old Troy get his drugs, without alerting the culprit. Everyone would think it's the same old drugs that Aiden always gets for his father.

Aiden always passes on his new findings to his father, through his most trusted guard called Tony. As a result, they decided to utilize his services once again. There was no plan of changing personnel because the culprit wouldn't expect Aiden to have come up with the antidote to the poison so soon. Going through another person would rather alert the enemy.