It was a complex potion to brew, even for two of them. And Granger was good at it. Not as good as Draco, but still good enough to consider her a perfect assistant. They worked all night together, only being interrupted by Weasley from time to time when he was bringing them one thing or another. Sometimes those were missing ingredients, sometimes a pot of tea with biscuits. And in the morning, he appeared with two mugs of freshly brewed coffee.