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I reread the series every summer, and still, there are many events that continue to upset me as if it's the first time I've read them. Like when Sirius had to flee because they had nothing to prove his innocence.
I considered the use of Veritaserum, but after reading something JK Rowling said about the potion not being sufficient evidence (because highly skilled wizards would be able to fight it or something like that, i ruled it out. and the pensieve, the pensieve is out of the picture too, as well as legilimency and occlumency because it's possible to create false memories and ideas.. as stated by Slughorn in HBP. But they could've taken the Minister with them back in time, so he could witness the conversation that took place in the shrieking shack. no meddling with time. or if that would be too risky, maybe they could've hidden somewhere by the trees to see, at least, that Pettigrew is still alive. maybe someone can show me that I'm missing something so I can put my mind to rest?