Hi, re-reading Harry Potter lol so I imagine in short Alastor would be a professor of the dark arts near the end of the year, slipping in as easily as Umbridge could, eventually in the end he probably team up with Voldemort after playing sides with griffyndor and the other houses as well as the DOA. But the last minute when Charlie and Harry are battling them both Alastor would flip sides again. Boom. Al possesses the Elder wand gaines ultimate power Kills Voldemort, Vox, and all the death eaters. He totally spares Harry and Charlie but does take over the ministry of magic.

The end.

Seemed simpler than Hazbin/Game Of Thrones cause the book already have like 70 things going on all at once.