28 Magical Facts about Dumbledore You Probably Haven’t Heard Before
Ariana’s corpse is Dumbledore’s boggart
We got a glimpse of Dumbledore’s guilt over his sister’s death while he drank a potion — Emerald Potion to be exact, according to Pottermore (now called Wizarding World) — that drove him mad on the night of his death. He cried out as if he was watching Grindelwald hurt her, begging to be killed instead. He felt such intense guilt his whole life that she was even his boggart. His greatest fear was that his spell was what killed her.