"All that inbreeding probably," Q observes sagely.
He shudders. "No wonder he went mad. I don't suppose he married his mother?"
Q naturally catches the implication. Molly Weasley is clearly not one of Severus' favourite people. "Or to see if poor Percy would do as rotten a job as she did. Misery loves company." Q blinks, trying to work out if that's a compliment or not. "Thank you," he finally says.
"Hmph!" Q snorts, also quietly. Modesty is all very well and good, but there's no harm in taking credit where it's due. "Really?" He's delighted. "You'll make a fortune with that one Severus. What's it called?" He shakes his head. "I won't. They're not efficacious at all. Dinner and a movie work much better." He begins to pick the seeds off one of the strawberries. "I know a song about love potions," he says absently.