What was the brother story in Harry Potter and the Deathly Hallows?

Answer 1

I'm assuming you're referring to the Tale of the Three Brothers in Tales of Beedle the Bard. It is about 3 brothers who cheated Death and Death rewarded them each. The first and second brother got killed by Death himself, as they boasted about their reward(The Elder Wand and the Resurrection Stone). But the third and youngest brother, who had the Invisibility Cloak, escaped Death. He then gave the Invisibility Cloak to his son. These three items make the Deathly Hallows and if any person had all three at once, the person is deemed Master of Death.