When Harry tricked Lucius Malfoy into giving dobby a sock, Lucius became inraged and used the killing curse in an alternate universe maybe he would have been stopped before he could have finished it, But in this universe Lucius Struck Harry Potter with the killing curse.
As Harry Potter fell to the floor Minerva McGonagall came around the corner and watched in horror as harry was killed by Lucius malfoy and the killing curse.
She disarmed him and then Restrained him before calling for Dumbledore, Amelia Bones and Madam Pomfrey.
She went to harry potter's side And asked a Sobbing house elf what had happened.
Dobby told her everything About the chamber and how the great Harry Potter freed him and then hiw his former master killed him.
Just as Dobby finished talking all the people Minerva had called for arrived, and they were all horrified to see that Harry Potter was dead.
Minerva explained everything and just as she finished talking a miracle happened and Harry potter got up with a huge gasp of air And then he did the most ridiculous thing He asked if everyone was okay Worried that Lucius had harmed or killed anyone else, not caring about his own well-being.
Harry Potter the boy who lived had lived again.
The next day it was all over the newspapers that The boy who lived had lived again After Lucius malfoy struck him with the killing curse Beacuse he had Saved a house elf.
Lucius Malfoy tried to claim the Imperius Curse defence again But he went to trial and was Forced to take Veritaserum, where he confessed everything including that the dark mark Could be only taken willing.
So after it was revealed that the dark mark couldn't be forced on someone, all the people who claimed they were under the Imperius Curse where found and captured and forced to stand trial where they were given Veritaserum.
After that Harry Accidentally Started a trend by cutting of his sleeves on his Robes, Showing that he had no dark mark. It became extremely popular and if someone had Their sleeves they were watched Suspiciously.