Harry Potter and the Order of the Phoenix Theme of Isolation

As Harry shouts to Professor Dumbledore after Sirius has died, "People don't like being locked up!" (37.131). In Harry Potter and the Order of the Phoenix, both Harry and Sirius spend long periods of time trapped where they don't want to be: Harry gets stuck with the Dursleys over the summer holidays (blerg) and Sirius must stay at Number Twelve, Grimmauld Place all year to avoid Voldemort and the Ministry. Both of them start to go stir crazy from the isolation. Harry, who is only stuck alone for the summer, contents himself with throwing tantrums. Sirius is the one who keeps going out in public even though he is a wanted murderer.

The theme of isolation in Book 5 is not limited to physical isolation. Harry also experiences intense social isolation because few people believe that he is telling the truth about Voldemort rising again. There's almost nothing as isolating as being thought crazy by pretty much everyone around you. What is more, Harry has a unique destiny. According to the prophecy, he is the one who has to kill Voldemort or be killed. That's a totally isolating experience: to be marked for a destiny that no one else around you can share.

1. Harry is isolated by his peers, many of whom think he's crazy, unreliable, or both. But he also actively isolates himself by turning away from his friends and trying to get through the challenges of Book 5 alone. Why does Harry reject help from Ron, Hermione, and especially Professor Dumbledore? What consequences does this rejection have?
2. How does Professor Dumbledore contribute to the isolation of both Sirius and Harry? What are his stated reasons for doing so? How could Professor Dumbledore have achieved his goals differently? What lessons does Professor Dumbledore learn about the dangers of isolation in Book 5?
3. Luna Lovegood seems pretty isolated from her fellow students. Why is she left out of Hogwarts social circles? How does Luna cope with this social exclusion? How does Luna's isolation start to effect Harry's perception of her character?