The fun thing about being a fallen angel with little to no power? He can still read Dean fairly well. No matter how drugged up, for example, he was well aware of the differences between past and future Dean (or present Dean, for him). So that very mild discomfort Dean feels? Yeah, Cas can totally tell, and he lets it roll off him with a smile.

Roll off in this case means he swallows it like a bitter pill and pretends it doesn't matter. It's the end of the world, etc. etc. blah blah, who has time to be eloquent.

"Wouldn't you like to know."

The truth is, he hasn't laced anything with anything, which is a damn shame, but his ressources are limited and he has to be careful not to use them all up. He's thought about it, honestly, but there's always the chance that someone in this house gets all 'well-meaning' and 'nice' and 'helpful' and destroys the food because Cas has consumed enough to get high (or full). So, no. Not unless he's alone. With a wink, he hands Dean one plate.

"Besides, weren't you going to stop trying to label everything I take, Dean? You're gonna give yourself a headache, you know."