Index · potion · book 4
Veritaserum
A truth potion. Three drops, and the stories treat the answers as compelled — and still not the whole truth of a person.
Veritaserum is interrogation in a bottle. The ministry and the school both reach for it when they want a confession without a long conversation. Compelled speech is not the same as understanding. A person can tell what they believe, or what they saw, and still leave the motive untouched.
The journal will not describe a recipe. Canon fact: the potion exists and is tightly controlled in the story. Using it on a student is treated as an abuse even inside a world that owns such a thing.