ohdeerboy:

Slughorn: “Look sharp, Tom, you don’t want to be caught out of bed out of hours, and you a prefect…”

Slughorn: “Ask away, then, m’boy, ask away…”

Tom: “Sir, I wondered what you know about…”

Slughorn: “Tom, that’s very Dark stuff, very Dark indeed.”

Slughorn: “Well, it can’t hurt to give you an overview, of course. Just so that you understand the term. A Horcrux is the word used for an object in which a person has concealed part of their soul.”

Tom: “I don’t quite understand how that works, though, sir.”