"I'm not 'in control'," Snape sighed. "You always did have this overly concrete way of thinking about the mind," he grumbled. "Thinking of Legilimency as 'mind-reading', as if the mind's a book.
The mind's not a potion either, where combination of these ingredients will produce that result. Control?" He snorted and shook his head. "To 'control' the mind in the absolutist way you suggest," Snape declared grimly, "requires Imperius or spells of that ilk."
"The most I can ever do is to suggest, guide, provide examples. All the real work - weaning himself off caffeine and sugar, paying attention to his emotions, endeavouring not to suppress them - has always been done by Al."