"If there are no more questions, you may find a partner, turn to page 357, and begin. One of you should record your observations at each stage of the preparation," Slughorn says. He pauses (and they all know it's a pause, for dramatic effect, and more is coming.) "Oh, and twenty points to the team that produces the best Epione Potion."

Lily likes the days Slughorn has them work in pairs.

Because (and she knows this is petty and childish, but she can't quite help it) it means that the one person in their year who might be as good at Potions as she is (and her former best friend) is going to be stuck working with the dead weight that is one of his fellow Slytherins.

And Lily?

Well, Lily gets to work with James.