Leo stood, wand still pointing at Marisa as she lay flat on the ground. He glanced from Marisa to Draco, who had just vomited another five slugs, and hesitated. This was one of the most awkward moments so far in his effort to not take sides between Marisa and Draco.
He hesitated before moving over to Draco. "You all right?"
Draco shook his head and another particularly large slug fell out of his mouth. "Let me… jinx her…" he said.
"You can if you like," said Leo, "but bear in mind she'll take revenge if you do."
"That would be – " A slug interrupted Draco's words – "revenge."
"Not in her book – the slug attack was revenge for you calling her a Mudblood, so you're even and she's free to retaliate against anything else you do."
Someone had countered Leo's Full Body-Bind while he had been busy with Draco, and Marisa was back on her feet.
"Exactly!" she said, looking smugly at Draco. "I'll duel you, if you want. Bet I can beat you."
Draco, reluctant though he was, knew when he was beaten. He lurched away, stopping every few steps to throw up more slugs, and turned back to fire off one last remark: "Your days at Hogwarts are numbered!"
"So are everyone's," said Marisa, not looking at all bothered by this unsubtle threat.
Leo, smiling a little despite himself, turned back to the group. "What have we learnt from that?" he asked.
"Don't get on the wrong side of Marisa?" suggested a Ravenclaw first-year.
"Well, that is a valid point," said Leo, "but it wasn't the one I had in mind."
Terry raised his hand. "Don't get distracted?"
"Exactly," Leo said. "The reason I was able to hit Marisa was that she was focused on Draco, not on me."
"I could have beaten you easily," Marisa added, grinning. "I just chose to target Draco instead."
"Yes, but you were meant to be duelling me, not Draco!"