A good one should have an engaging plot. For example, it could be about how Harry's discovery of the Phoenix affects his magical abilities. Also, the characters should be in - character. Harry should act like the Harry we know from the books. And the writing should be of good quality, with no major grammar or spelling mistakes.
Characteristics of a good 'Harry - finds - a - Phoenix' fanfiction can be many. Firstly, the story should be unique. Instead of just repeating the known facts about Phoenixes from the books, it should offer a fresh perspective. For instance, the Phoenix might have a special connection with Harry that is different from what we expect. Secondly, the pacing of the story is important. It should not be too rushed or too slow. If it's about Harry finding a Phoenix, the discovery should be a significant moment, and the events that follow should unfold at a reasonable speed. The fanfiction should also have good dialogue. The conversations between Harry and other characters, including the Phoenix if it can communicate, should be natural and add to the story. Also, it should respect the existing Harry Potter universe while still being creative enough to stand out.
Well, in a great Harry - finds - a - Phoenix fanfiction, the relationship between Harry and the Phoenix should be well - developed. It could show how the Phoenix helps Harry in his battles or in his personal growth. The fanfiction should also be set in the magical world of Harry Potter in a believable way. The descriptions of the Phoenix, its powers, and its behavior should be detailed and based on what we know from the original series. Moreover, a good fanfiction might introduce some new and interesting elements related to the Phoenix that still fit within the overall lore of Harry Potter.