Question

Who 1st told Harry the Dementors had been authorized to give Sirius the kiss?

Answer 1

Answer: Harry directly heard it during a discussion between Professor Severus Snape and Cornelius Fudge

Explanation: After awakening in the hospital wing after falling ill after coming in contact with Dementors during a Quidditch match, Harry overhead Severus Snape and Cornelius Fudge discussing the fact that Sirius Black will be receiving the kiss.

Answer 2

Arthur Weasley is the one who first told Harry about the Dementors' authorization to give Sirius the kiss in 'Harry Potter and the Prisoner of Azkaban'.

Step-by-step explanation:

In the Harry Potter series written by J.K. Rowling, Arthur Weasley is the one who first informed Harry that the Dementors had been authorized to administer the Dementor's Kiss to Sirius Black, should they capture him. This occurs in Harry Potter and the Prisoner of Azkaban, during a time when Sirius Black, who is believed to be a dangerous felon, has escaped from Azkaban prison and the Dementors are in pursuit. The Dementor's Kiss is the process by which a Dementor sucks out a person's soul, effectively leaving them in a state akin to death without actually dying.