She had finished brewing the potion days ago. The vial stored securely in her bag until the opportunity to use it arose. Veritaserum had been the most difficult potion she had brewed yet, taking her well over a month to complete. And only a single dose to show for her efforts. It was a frustratingly temperamental potion, only effective if brewed in one dose batches. She had managed to keep it under her bed, working on it every evening. But by itself, she knew it was useless. That even if she managed to slip him the potion successfully, there was no way they would be alone at the time. No way for her to interrogate him about anything useful.