After a Quirk Slip that was also a first Quirk activation, people find themselves with memories that very much don't belong to them, and which they could have lived without, thank you very much ! Seriously, who would want to remember dying by Dragonfire, or Ice Zombies ?

A random discussion at Grimmauld Place during Harry's hearing leads Tonks to get a completely new idea about "the power he knows not" : Sometimes, repeated all-nighters disturbing the brain chemistry can prove actually constructive...