"Tom, you have someone different to confide in now. I'm not Ginny Weasley. If I don't get anything useful out of you, I'll destroy you outright."
Karn picked up his quill and wrote those words in the Diary. Before long, a reply appeared, though a trace of resentment could be felt in it.
'I will help you. That is my duty. When I was created, I was given a mission: to help everyone who obtains me.'
"What are the principles behind memory magic? What kinds of curse-based dark magic are there? What spell allows a wizard to fly?"
Karn did not beat around the bush. He wrote down many kinds of magic he did not yet understand in the Diary, including quite a few counters to dark magic. What interested him most, however, was the flying magic the Death Eaters often used.
Dumbledore and the Order of the Phoenix seemed to know it too, but Lupin had not taught him, so Karn could only turn his attention to Tom.
The flying magic used by the Death Eaters could keep up with a Firebolt, putting its speed at roughly 240 kilometres per hour. It was also extremely convenient, and he did not seem to have seen any drawbacks.
After Karn wrote down a pile of questions, replies slowly appeared in the Diary, which he quickly copied down.
"Tom, you scheming bastard! How dare you lie to me!"
A scheming bastard like Tom might have some trick up his sleeve, so after Karn finished copying his answers, he summoned a small wisp of Fiendfyre at his fingertip and began scorching the Diary from below.
'No, I haven't lied to you! These answers are all true. Please stop! Don't burn me anymore!'
"Stop? You're clearly lying to me. I have to teach you