Dumbledore asked Harry to give Kreacher an order to prove whether or not he had actually inherited Sirius' house (The Order of the Phoenix's hideout) like Sirius intended in his will. If he obeyed, then Harry had indeed inherited it (which is what happened) and if he didn't they would be forced to make other plans
Well, Kreacher was never pleasant to Sirius because Sirius was not nice to Kreacher, Sirius promised Harry that they would be a proper family but then died, etc.
Kreacher is the house elf for the Black family's home. After the death of Sirius, he becomes Harry's to command. Harry eventually wins Kreacher's affection.
Kreacher obeyed his order.
A shard from the mirror Sirius Black gave Harry.
No, you can only play as Harry, Fred, Sirius and Dumbledore.
Is it Order of the Pheonix? If it is you need to talk to Sirius leave the room and you will see kreacher
He inherits Sirius Black's house - Grimmauld Place and his house elf, Kreacher.
Well, Kreacher was never pleasant to Sirius because Sirius was not nice to Kreacher, Sirius promised Harry that they would be a proper family but then died, etc.
House elves are bound by strong magic that prevents them from refusing their masters order. In order to prove that Sirius Black's will was valid, Dumbledore summoned Kreacher and asked Harry to give him an order. Harry, trying to think of an order, told Kreacher (who was screaming obscenities) to "shut up!". Kreacher was forced to do so, proving Harry was his master and that the will, which listed Harry as the owner of Grimmnauld, was valid.
Kreacher is the house elf for the Black family's home. After the death of Sirius, he becomes Harry's to command. Harry eventually wins Kreacher's affection.
He inherits Number 12 Grimmauld Place, the house that the "Order of the Phoenix" uses as their headquarters and he also inherits the house elf Kreacher.
Kreacher obeyed his order.
What did professor Dumbledore give to Ron and Harry
A shard from the mirror Sirius Black gave Harry.
No, Kreacher the House-Elf is inherited by Harry Potter, whom Sirius Black named his sole heir.
No, you can only play as Harry, Fred, Sirius and Dumbledore.
Nobody was a death eater in disguise in Order of the Phoenix. This happened in Harry Potter and the Goblet of Fire when Barty Crouch Jr took polyjuice potion and pretended to be Mad-Eye Moody.