The flask was filling. Her blood, the thing that kept Sam coming back to her, trusting her, listening to her, it was trickling into the flask so Ruby would never have to worry about loosing him again, because thats what would happen if he started to logically, like a Hunter, think about the things she was having him do, the torture, even if it was of monsters. The brutal bloody murder.
It was to get him ready for Lucifer's return, get him prepared for the man he would then become. As he tore his gaze away from the flask and more tellingly struggling to do so, Ruby knew he was still her boy. But she also knew she didn't have long.
"Different huh? Because headaches are normal. This isn't normal Sam, nothing about this is going to be normal. Its drinking blood. The blood of a demon, no less. But I told you that it was going to be hard for a while didn't I. Told you you were gonna experiance things so against what you know. But it'll pass, it'll all pass. If it makes you crazy now, that just means you're strong, and close, so close."
And then she thought she might have it, might understand the true cause of all this.
"Sammy, are you ashamed cause you like how it tastes, how it makes you feel? You know its okay to like it don't you. You don't need to worry about that"
Her expression all sincerity and good intentions Ruby went in for the closing arguement.
"You've stuck with me this long, and you're doing so well, don't walk away from this now, not when you're so close to a breakthrough I can taste it. Please, for me..."