• Cast it on a stranger? This is where I am not sure. Arguably, you could get the same effect with a plate of brownies, but obviously doing it with magic is more insidious. Even then, though, the extent to which you invaded their mind wasn't going to allow you to do anything truly awful to them. The kind of favors that a "friendly acquaintance" can reasonably expect are pretty limited.
You already did something truly awful to them. You invaded their mind and subverted their will. It doesn't matter what you are trying to get them to do after that. It doesn't even matter if you were trying to get them to do something for their own good.