It could be Harry Potter himself. After realizing how he had been used, Harry might decide to hold Dumbledore accountable. Harry has the power and the motivation, having been through so much due to Dumbledore's actions or inactions.
Publishers pay for short fiction. This includes traditional book publishers when they are putting out an anthology of short stories, as well as magazine publishers. Some literary journals also pay for short fiction.
In many cases, the one who initiates or organizes the pirate feast is responsible for the payment. Sometimes, it might be a shared cost among the pirates. It all varies based on the story's details.
Often, it depends on the platform or publication. Some websites or literary magazines might cover the costs themselves, while in other cases, authors might have to pay for submission or publication fees.
Some contests offer cash prizes for winning short stories. Also, authors can sometimes get paid by companies or organizations that commission specific stories for marketing or educational purposes.